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Chapter 12 Search and Choice in Urban Housing Markets
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Behavior and Environment: Psychological and Geographical Approaches T. Garling and R.G. Golledge (Editors) 0 1993 Elsevier Science Publishers B.V. All rights reserved.
CHAPTER 12
Search and Choice in Urban Housing Markets W. A. V. Clark
Studies of residential search and choice now form a substantial and coherent body of knowledge (Clark, 1981, 1982a, 1982b, 1986). Methodological developments in discrete choice models (Wrigley, 1985), research in conjoint measurement (Phipps & Clark, 1987) and investigations of scaling models of choice (Timermans, 1984) continue to stimulate studies of search and choice at local and aggregate scales. It is not possible to do justice to the whole of this literature. The focus of this chapter is narrowed to studies which have explicitly incorporated the spatial context or a spatial structure into the research design. It is useful to examine what is still a reasonable structure for examining residential search choice questions and to place the more recent explicitly spatial contributions into that larger research context. The larger context is one in which the residential relocation process is divided into a decision to move, a decision to view alternatives (search), and the actual relocation behavior (the choice outcome itself). The decision to move is now accepted as a process of adjusting a (perceived) disequilibrium, sometime viewed as stress m u f f & Clark, 1978) but in every case a tradeoff between a current and an alternative residential location. The search process is driven by households falling out of adjustment and into disequilibrium as their housing composition changes. The search process is less clearly specified although there is a substantial body of empirical results which suggests a wide range of approaches to house search. The final choice is seen in the context of matching household needs to housing characteristics. (Figure 12.1) The investigations of search and choice in geography now have a two and a half decade history and the analytical and empirical contributions have provided a rich understanding of the dimensions of the search process (Clark 1981, 1983) However, as Montgomery notes (Chapter 13 of this book), we are still a good distance from being able to predict the
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likelihood of a move or the actual choice of a dwelling. The work that has been accomplished as sketched out in Figure 12.1 suggests a set of models which parallel the division of research into the likelihood of a move, the decision to search and the search process itself and the actual dwelling
MODELLING THE DYNAMICS OF SEARCH AND CHOICE DISEQUILIBRIUM MODELS OF THE LIKELIHOOD OF A MOVE I
V MODELS OF SEARCH
Decision to Search
4
MODELS OF INFORMATION
ACQUISITION AND USE
I
Relocation Behavior
FIGURE 12.1. The structure of research on search and choice in residential
mobility.
choice. The complexity involved in modelling choice and search has tended to generate research and models within one of these contexts and as yet there are no overarching models which truly link models of the decision to move and the search process. Hence it is better to think of the decision to move and the choice itself as the structure with the search process embedded within the overall mobility decision making. The multinomial hierarchical choice models (McFadden, 1978; Lerman, 1979; Lierop, 1981, 1986; Porell, 1982; Clark & Onaka 1985) have come closest to providing a decision making structure in which the choice to
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move is the primary choice, followed by the choice of area to search followed by the choice of house to select but empirical testing has been limited. Why Study Residential Search and Choice? For at least two decades the emphasis in behavioral studies of residential relocation was on why people moved and occasionally on the impacts of mobility on individuals and on the urban structure. Slowly, however, it became apparent that we needed to know much more about the complex interconnections between the urban structure and human behavior. It was no longer enough to show that people often moved short distances in neighborhoods that they were familiar with, that they moved to bring their housing consumption nearer to equilibrium consumption, that younger households moved more often or that tenure was important, (that renters moved more often and owners less often). It was important to relate mobility to the built environment and to ask questions about the interaction of search, choice, and impacts both on the changing neighborhoods of cities and, by extension, on the population composition of neighborhoods. The focus on mobility and choice for its own sake was replaced by a concern with the integration of the processes of search, choice, and urban structural change. The focus moved from studies of why people moved to what were the processes and impacts of population relocation. In turn it created a bipolar approach to understanding relocation behavior. Simple questions of why people move were replaced either with studies of the socio/psychological processes of decision making or studies of geographic outcomes. Understanding how people make decisions and understanding the choices that they make enriches our understanding of the general processes of behavior in the city and, by extension, our understanding of how neighborhoods change in the city. Just as studying activity patterns provides a way of assessing the relationship between environment and behavior, so studies of the search patterns and the choices that households make provides a link between the built environment, the neighborhoods of the city, and the people who live in them. Why do certain households end up in certain locations, and how are choices of locations affected by search and selection? These are questions which arise from a focus on residential search and choice when those topics are linked to the urban built environment.
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A concern with residential search and choice is more than a way of linking behavior and urban structure. It also allows us to raise important questions about how housing opportunities are known and used, and on the spatial extent of peoples' experiences of the built environment. Even more important, the search and relocation behaviors raise questions about the extent to which choices are exercised freely or are constrained by household factors and factors of the market. For a time investigations of residential migration emphasized household preferences and unconstrained choices (Clark, 1981; Rossi, 1955). A counterbalancing perspective (Murie, 1974; Barrett & Short, 1979) emphasized the constraints on the mobility process which arise from the structure of the housing market itself and the actions of institutional actors in the housing market. To some, the actions of individual households were better explained by the nature of the housing system than consumer preferences (Barrett & Short, 1979), to others the individual choice process was still the primary explanation (Clark, 1986). Now, most research takes a middle ground with the actions of individuals grounded in the structure of the housing market. While individual households are necessarily constrained by the availability of housing by tenure, price and location, at the same time there is considerable evidence of individual choices in both controlled and less controlled housing markets pieleman, Deurloo, & Clark, 1989), and that the same processes are at work in both controlled and uncontrolled markets pieleman et al., 1989). Even though there are still vigorous debates about choice and constraint, in the end studies of search and choice in the housing market will be important to the extent that they inform policy. While the extent of the spatial search for new housing is probably only peripherally related to questions of housing provision, a better understanding of the preferences for particular tenures, a better understanding of locational preferences and how those preferences are formed and how they influence choices in the housing market are an important part of understanding how the urban structure will evolve. Current interests in urban restructuring, in polycentric urban forms and the spatial organization of a pluralistic urban form will be better served by a theoretically informed understanding of residential search and choice.
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The State of Knowledge
To reiterate, initial studies of residential migration revolved around "why did a household move" and "who got what" in the housing market when they moved.The emphasis was on choice of tenure, choice of housing composition (size, amenities and so on) and choice of location. The studies were designed to explore the question of why people moved, and why they chose a given location and a given house. The research from this approach documented that people moved to improve their housing situation, to increase their space, to own rather than rent, and to improve their accessibility within their locational context. A quantitative evaluation of the choices emphasized the housing context as the explanation of their choice rather than the neighborhood or the environment. But even though this initial research has now provided a rich documentation and understanding of residential choices, and serviceable models of the way in which disequilibrium in housing consumption leads to the decision to move, the "moving process" itself was at least initially neglected. However, by the end of the decade of the ~ O S studies , of search had provided a set of new conceptualizations and documentation of the empirical nature of search. Implicit Spatial Models of Search There are two sources for much of the initial research on residential search and choice. On the one hand, marketing and economics provided basic models of "search", and, on the other hand, psychology focused on choosing among alternatives. While marketing has some similarities with the psychological approaches, economics built a strong theoretical approach to the process of "stopping search". Such models focus on the issue of when to accept an offer (usually a job offer), versus continuing to search and to incur the associated costs. The job search literature (Clark & Flowerdew, 1982) emphasizes the influence of information and the way in which uncertainty and the flow of information influence the decision to continue searching. As in other work by economists, the emphasis has been on the nature of optimum search strategies within utility-maximization frameworks (Phipps & Laverty, 1983). There have been attempts to frame housing search in this context (Ioannides, 1979). The large literature in psychology is more concerned with choice among alternatives (which of course implies the existence of a search and evaluation process).
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The emphasis in the psychological literature is on how alternatives are evaluated rather than how they are collected and identified. The focus extends to the role of information and opinion revision rather than identification. To psychologists, choice emphasizes individual judgments. These are often judgments of sets of alternatives conveyed to a panel and do not include identification of alternatives. The latter may be more central in the residential decision making environment. (For a discussion of the psychological approach, see Slovic, Fischoff, & Lichtenstein, 1977; Clark & Flowerdew, 1982.) Geographers borrowed from this work and evaluated the use of stopping rule models (Flowerdew, 1976) and disequilibrium approaches to residential mobility in general (Smith, Clark, Huff, & Shapiro, 1979). But, again as in the economic approaches, these models were only implicitly spatial and there was a tendency to treat space or location as simply one attribute of the alternatives to be considered. Even so, in the Smith et al. (1979) presentation, although space was implicit it was an important component of the model. The expected utility attached to search for a dwelling in ''a given neighborhood" is based upon the household's prior estimates of the housing characteristics in the area and the expected costs of search in that area (Smith et al., 1979). Thus, neighborhoods are clearly a part of the model but are the context in which search occurs rather than the defining characteristics of the process itself. These notions of the search process as a utility-equilibrium process emphasize that an individual's decision to search is a function of the difference between the expected utility of further search and the utility of the best vacancy found to date (Clark & Smith, 1982). As the model is neighborhood (or community) based, individuals compute the locational stress of neighborhoods in the city and search in the neighborhood which gives rise to the largest positive stress value, that is the neighborhood where the likelihood of success is greatest. A vacancy with greater utility than the current house (or vacancy) becomes the best alternative, and search continues until stress is driven to non-positive values in all neighborhoods. A test of the model in a section of Los Angeles provided some support for the process described by the model. Models of spatial reside& search. In contrast to the Clark/Smith equilibrium approach, Huff (1986) provided two classes of models which are truly spatial, focusing on the nature of selection from areas and in relationship to search constraints (Figure 12.2). The area-based search model is the outcome of considering the search process as one in which households make the decision to visit a particular vacancy conditional on
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the area containing that vacancy. Areas with large numbers of vacancies have a greater chance of being included in the search space. But at the same time the prior search experience of the household influences the likelihood of visiting particular areas. Selecting an area is followed by a more intensive activity in that area with high probabilities of visiting vacancies near the last vacancy visited. Huff (1986) provides a formalized model of these observations, and in a test of the model in a part of the Los Angeles region, shows that households tend to persist in submarket search once an area has been identified and "provides strong behavioral evidence of the existence of geographically defined submarkets that limit the domain of search for individual households" (Huff, 1986, p. 217).
FIGURE 12.2 The spatial context of search based on Huff (1986).
The anchor-points search model also assumes that the observed search pattern reflects the underlying distribution of vacancies. However, in this case the bias in the spatial pattern of search is related to locational preferences of the household and specifically of the way in which a household concentrates search in a small area around a focal point. Search declines in intensity around the focal point. The empirical basis for this model suggests that a subset of households employ a locationally persistent search strategy by which they concentrate effort near the mean center of the search pattern. That the anchor-points model was able to match the observed search distribution over 50% of the time is convincing evidence of the importance of anchor or reference points in the search process. Both the area-based and the anchor-point models provide evidence of the strong spatial regularities in residential search. These models demonstrate that it is possible to build operational search models which build space
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into the search process in such a way that we can predict where households will search and, by extension where they will move.
The Intersection of Search, Choice and the Housing Market Environment An important element of the Huff (1986) search models is the recognition of variation in the housing market. Housing markets are differentiated spatially. They are differentiated by tenure and by price, It is this differentiation which underlies the creation of residential environments which are reflected in the search and choice process of individual households. Households do not search and choose in a vacuum. They are able to segment the housing market by these important variables which then enter into the search and choice process (Bourne, 1981). A generally accepted view is that submarkets for housing do exist but at the same time there is only a limited literature devoted to defining their structure, and even less on the way in which these submarkets influence search and choice. Even so, some form of spatial segmentation is at the heart of the discussions that we have introduced in this chapter. There are clearly identifiable areas (by price, quality, accessibility, and so on), and it is these areas which help define the search process. Bourne (1981) has suggested that at the smallest spatial scale, the neighborhood scale, the only distinguishing feature of the housing market is that of limited spatial entity. Of course the difficulty is in defining that spatial entity. To date the definitions of submarkets are pragmatic statistical decisions and not theoretically based interpretations of the links between households and the housing stock. Beyond that we need additional studies of the links between the submarkets and the way they influence the search process. The models introduced by Huff (1986) are a beginning.
Empirical Observations on Search While the models have been developed to conceptualize the process of housing search there has been a number of studies designed to document the dimensions and characteristics of search. These empirical investigations have evaluated the length of search, the spatial extent of search, and the information used in the search process.
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Economists have identified these factors as measures of search effort and search costs. For geographers there has been an attempt to create a picture of the search activities of households. Another way of thinking of these factors is to think in terms of the dimensions that they represent. They are dimensions of time, (length of search; how may alternatives does a household view? and how long do they search before making a decision? what rules does the household use to make the decision?), space (the spatial pattern and extent of search; where does the household look?) and information (the nature and use of information in the search process) (Huff 1986). To some extent these dimensions have been discipline specific. Economists have focused on the issues of stopping, hence on issues of the length of search. Psychologists have emphasized the role of information processing, and geographers have been more concerned with empirical estimates of the spatial nature of the search. On each of these topics however, there is a substantial body of empirical information. Length of search. The surprising finding that housing search is a relatively short process still stands. Barrett (1973) in studies in Toronto, Canada and Hempel (1969) in Connecticut in the United States, pointed out that a third of all home buyers and half of all renters consider only one alternative. Clark (1982) found that recent home buyers in the Los Angeles area searched less than a month, within an area of about 3 miles radius, and looked at about 15 houses. Mackett and Johnson (1985) reported that three quarters of the searches by owners were completed in six months and half within three months. Of course, length of search and the number of units searched are closely related. An important part of the search for housing is the relationship with the urban environment and the necessity, despite recent telemarketing of houses, to visit neighborhoods and houses within neighborhoods. Measures of search intensity - houses visited, neighborhoods and communities searched, the distance of search and the length of search all confirm the limited time and narrow spatial context of search (Figure 12.3). The diagrams reported for Los Angeles in the figure can be replicated for other metropolitan areas and in other cultural contexts. They provide an important empirical basis for the area and anchor point search models designed by Huff (1986). There have been numerous suggested explanations for the relatively short search time. These hypotheses are drawn from economic approaches to search. Until now they have not been examined within psychological approaches to choice and decision making. The first explanation assumes
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that households are satisficers and are quite risk averse in their selection of alternative houses. Smith et al. (1979) suggested that the satisficing behavior leads households to stop search when they have found a unit with certain minimal conditions. A second explanation calls on the cost of search as a constraint in the search process. If we include within the cost of search the personal energy cost as well as foregone earnings and real dollar outlays for travel and other activities, this hypothesis can be a compelling explanation for the shortness of search especially when, in the case of renters the choices can be further modified within a relative short period of time. That renters search much shorter periods and examine fewer alternatives is direct evidence that households are aware of the search cost to returns ratio. Although some have suggested that data collection may not have identified all the alternatives and that prior to active search there may be a sifting of alternatives, this is less easily tested. Goodman (1976), in particular, has identified a series of testable propositions concerning the optimal length of search and the nature of the stopping rule employed by households given that the search model accurately describes search behavior. Three of the propositions may be directly related to the general explanations of limited search. If G is the
Search Intensity
Length of search (web)
Number of houses
Y
E
te
L
1
2
3
4
5
6
Number of areas
FIGURE 12.3 Distributions illustrating intensity.
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distribution of net gains to the household for all vacancies (or areas) in the domain of search (gains relative to the household's current living condition), then the following propositions should be true (Huff, 1982): 1) Given the known costs of search and the expected utility or net gain from search, there is some minimum net gain, g, such that any vacancy found with a net gain g greater than or equal to g will be selected even though further search might uncover a better alternative; 2) the greater the variance of the G distribution, the greater is the expected number of units searched; and 3) the lower the costs of search relative to the expected value of G, the greater is the expected number of units searched. Although there are no direct tests of the propositions, the available evidence offers general confirmation. If the gains are smaller and the distribution has less variance (rental units versus houses), then renters should search for shorter periods. This has been confirmed (Michelson, 1979; Rossi, 1955, Speare, Goldstein, & Frey, 1975). Meyer (1980) has shown that the size of the household's choice set is likely to be a function of the amount of variance which exists in the population of alternatives (Meyer, 1980). For proposition (3), the support seems to come in the main from studies of the search behaviors of low-income households. Their search behavior is constrained by resource limitations including poor access to private transportation (Cronin, 1982). They face higher search costs relative to the total resources available and hence curtail search. The spatial context of search. There is still only a small group of studies which have effectively measured the nature of search in and across residential neighborhood contexts. The approaches to spatial search have been divided by Huff (1986) into studies, first, which focus on the areas searched and more particularly on the number of housing units examined in a set of neighborhoods and, second, studies which identify a point pattern of houses and locations which are in the search space. In addition to these two conceptual approaches, prior empirical contributions have been largely descriptive. They provide detail on the more limited areal searches conducted by low income and minority households and more extensive search patterns of higher income households. The combination of a restricted set of vacancies available to low income and minority households, and the general likelihood of searching in familiar areas (especially for lower income households) explain the spatially biased patterns that emerge.
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The spatial context within which search occurs has also been of some concern to policy makers and especially those concerned with the increasing inner city suburban dichotomy. Deurloo, Clark, and Dieleman (1990) have provided evidence of the constrained nature of residentialrelocation behavior. The latter study showed how in The Netherlands household choices reflect their initial locations. Households relocate by making choices in residential environments very similar to those in which they originate, while owners (with generally higher incomes) can effect less constrained choices. In general, search and choice are constrained processes. Information and search and choice. It has long been established that the availability, amount, and quality of information have a direct influence on the nature of the choice process. Detailed information of relative prices and the prices of alternative units will enable the decision maker to make a more informed decision. However, while there is valuable data on information use in general (Table 12.1), the application or linking of information and residential search is still fragmentary. Most empirical studies have been concerned with the amounts and types of information available to searchers in the housing market, but even these studies have in the main provided only general information on the differences in information use by income. Barrett (1973) provides support for Rossi's (1955) observation that lower-income households rely more heavily on personalized information sources such as friends and family. Palm (1976) has shown that real estate agents spatially bias the information provided to searchers. Other studies stress the changing nature of the information source over time (MacLennan & Wood, 1982). As search proceeds, the importance of personal knowledge and the use of friends and relatives decline and newspapers increase in importance. In the later stage, general areal information is replaced with specific data on housing availability. Mackett and Johnson (1986) use survey data to show that ideas change during the search process, perhaps as the result of information processing. Several empirical studies focused on the relative roles of different sources of information. Sources varied from real estate and newspapers to signs, building contractors, and co-workers. But how are the sources used? What is the sequence of use? Although some information is provided by Clark and Smith (1979), the role and impact of information channels is still a largely unexplored area. Clark and Smith (1979) showed in a simulation study that searchers are sensitive to the cost of information and their search efficiency is significantly less with high cost information.
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Of some interest to realtors is the (not unexpected) result that good agents speed up the process of search. Other approaches focus on the provision of information rather than on its consumption. Such studies highlight another important dimension of trying to understand the process of search and choice. An analysis of real estate advertisements by both realtors and homeowners provides very different conceptions of the provision and use of information. In short, while both owners and realtors provided detailed price information (though fluctuating over time), in general owners provided much more exact location information than realtors. While realtors wish to take buyers to houses and to "sell houses", owners clearly wish to give buyers the opportunity for independent non-involved inspection (Smith, Clark, & Onaka, 1982). Of course, it is also more efficient for owners who need not show the house to every possible purchaser. The study was not able to provide definitive conclusions of the way in which information varied over time, but there was some evidence of changing information provision in stable and price escalating markets (Smith et al., 1982). TABLE 12.1
Relative Weighting of Information Sources Used in Housing Choice Source type
Citation
Real Estate
News- Relative/ paper friend
Walking/ riding around
Signs Contnctors
Did not search
Other ~
Rossi (1955) Hempel(1970) Barren (1973) Hehrt(1973) Spare (1975) Michelson (1977) Goodman(l978)
11 38 24 18 5 25 21
15 25 15 18 17 26 16
38 12 21 36 19 15 22
15 4
6
25 11 32 28
12 10
35
6 4
20 15 3 17 3
-_ 6
Finally, there is still only limited research on residential utility functions, yet such research may be central to understanding the way in which households choose particular dwellings. Moreover it is this research which brings closer links between the work of psychologists, geographers and economists. Phipps and Clark (1988) were able to document an adaptation process of residential preference formation which may account
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for some of the difficulty in generating models of the search and selection process. The work suggests that innate residential utilities of households are being modified by their experiences in their local housing markets. The interaction of preferences and the local housing market are a critical element of understanding search behavior.
New Directions: Where Do We Go From Here? Recent analyses of hierarchial search have been somewhat concerned with mathematical specificity rather than empirical evaluation and both these and previous works do not yet have an overarching organizing theme (Jayet, 1991). However, research on residential search and choice can be fitted into a developing theme which has been suggested as a way to view the processes of moving, locational and housing choice. Within the last decade the concern to develop a conceptual structure within which the notions of housing choice and residential mobility can be embedded has led to a focus on the housing career and the life course as approaches to understanding the complex interrelated activities of search and choice. Kendig (1984, 1990) used the notion of housing careers as an organizing principle to examine the intersection of housing choices and family composition. Kendig (1990) attempts to form a link between the housing tenure decision on the one hand and the family life cycle on the other. To do this, he suggests that housing careers are the means for linking mobility and the life cycle. In this sense he is building on the work of Michelson (1977) who suggested that households pass through a series of dwellings that increasingly meet their long term housing aspirations. The paths of individual households through the housing stock are influenced by broader social changes as well as life transitions and local housing markets. In this sense the notions of housing demography link the life course (path of the individual), the housing career (the housing units that the household occupies), and the social economic changes in the household itself. The life course is an even broader context in which the housing career can be situated. Mayer and Tuma (1990) have summarized the notion of the life course as a concept for viewing the progress of an individual or groups of individuals (or even institutions) through their lives. This process though life can be viewed as a sequence of events. The event list includes a wide range of occurrences from events related to education, to family formation, to career decisions, and not the least to housing and
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shelter decisions, in turn interrelated with the decisions about family and career. Much of the research in life course analysis has focussed on the individual life span and the way in which it is shaped and organized, not just by the decisions of individual actors but by the cultural beliefs of the individual and both the social and spatial context in which the individual is situated. The aim of life course analysis is to look at individual life events and the patterns of life trajectories (the terminology of housing careers is quite similar) in the context of the social processes that generate these events and trajectories. In the past there was much attention directed to the issue of spatial mobility as such and search behavior was simply an associated activity which might create greater understanding of the mobility process. Increasingly however, the focus is not on spatial mobility as such, nor on the relationship of search behavior as related to spatial mobility; rather the focus is on the analysis of the dynamics of the separation between work and residential locations. Search then becomes important to the extent that it provides an understanding of how work and residence relationships influence mobility and housing choice. New work will necessarily address the complexity of the decision making process in which spatial change both in the city and between regions is the process whereby households link work and residence and the processes of mobility, migration, and commuting are used to effect that linkage. The life course can be used to study the events and the timing between the events of the decisions to search, to move or commute, and/or to change jobs, as events in a trajectory of change over time. This conceptualization may provide the structure for a dynamic and interactive approach to choice and decision making in space.
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Clark, W. A. V. (1982a). Modelling housing market search. London: Croom Helm. Clark, W. A. V. (1982b). Recent research on migration and mobility: A review and interpretation. Progress and Planning, 18, pp. 1-56. Clark, W. A. V. (1986). Human migration. Newbury Park, CA: Sage. Clark, W. A. V., & Flowerdew, R. (1982). A review of search models and their application to search in the housing market. In W. A. V. Clark (Ed.), Modelling housing market search (pp. 4-29). London: Croom Helm. Clark, W. A. V., & Onaka, J. (1985). An empirical test of a joint model of residential mobility and housing choice. Environment and Planning A , 17, 9 15-930. Clark, W. A. V., & Smith, T. R. (1979). Modelling information use in a spatial context. Annals of the Association of American Geographers,
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Clark, W. A. V., & Smith, T. R. (1982). Housing market search behavior and expected utility theory 11: The process of search. Environment and Planning A , 14, 717-737. Clark, W. A. V., & Van Lierop, W. (1986). Household location. In P. Nijkamp & E. S.. Mills (Eds.), Handbook in regional and urban economics. pp. 97-132. Cronin, R. (1982) Racial differences in the search for housing. In W. A. V. Clark (Ed) Modelling housing market search (pp. 81-105). London: Croom Helm. Dieleman, F. M., Deurloo, M. C., & Clark, W. A. V. (1979). A comparative view of housing choices in controlled and uncontrolled markets. Urban Studies, 26, 451-468. Deurloo, M. C., Clark, W. A. V., & Dieleman, F. M. (1990). Choice of residential environment in the Randstad. Urban Studies, 27, 335-35 1. Flowerdew, R. (1978). Search strategies and stopping rules in residential mobility, Transactions of the Institute for British Geographers, 1 , 47-57.
Golledge, R. G. (1982). Substantive and methodological aspects of the interface between geography and psychology. In R.G. Golledge & J. Rayner (Eds.), Proximity and preference (pp. xix-xxxix). Minneapolis, MN: University of Minnesota Press. Goodman, J. (1976). Housing consumption disequilibrium and local residential mobility. Environment and Planning A , 8, 855-874.
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Hanushek, R. & Quigley, J. (1978b). Housing market disequilibrium and residential mobility. In W. A. V. Clark & E. G. Moore (Eds.), Population mobility and residential change (pp. 5 1-98). Evanston, IL: Northwestern University. Hempel, D. J. (1970). A comparative study of the home buying process in two Connecticut markets. Storrs, CT: Center for Real Estate and Urban Economic Studies, University of Connecticut. Huff, J . 0. (1984). Distance decay models of residential search. In G. Gaile & C. Wilmott (Eds.) Spatial Statistics and Models, (pp. 345366). New York: Reidel. Huff, J. 0. (1986). Geographic regularities in residential search behavior. Annals of the Association of American Geographers, 76, 208-227. Huff, J. 0. & Clark, W. A. V. (1978). Cumulative stress and cumulative inertia, a behavioral model of the decision to move. Environment and Planning A , 10, 1101-1119. Ionnides, Y. M. (1979). Market allocation through search: Equilibrium adjustment and price dispersion. Journal of Economic neory, 11, 247-249.
Jayet, H. (1991). Spatial search process and spatial interaction: 2, Polarization of concentration, and spatial search equilibrium. Environment and Planning A , 22, 719-732. Kendig, H. (1984). Housing careers, life cycle, and residential mobility: Implications for the housing market. Urban Studies, 4, 271-283. Lerman, S. R. (1979). Neighborhood choice and transportation services. In D. Segal, (Ed.), 7he economics of neighborhoods (pp. 83-118). New York: Academic Press. Lierop, Van W. F. J. (1986). Spatial interaction modelling and residential choice analysis. Aldershot, England: Gower . Mackett, R. L. & Johnson, I. (1985). Residential search behavior: The implications for survey and analytical design. Ejdschrifr voor Economishe en Sociale Geografle, 76, 173-179. MacLennan, D. &Wood, G. (1982). Information acquisition: patterns and strategies. In W. A. V. Clark (Ed.), Modelling housing market search. (134-159). London: Croom Helm. Mayer, K., & Tuma, N. (1990). Event history analysis in life course research. Madison, WI: University of Wisconsin Press. McCarty, K. (1982). An analytical model of housing search. In W. A. V. Clark (Ed.), ModeEling housing market search (pp. 30-53). London: Croom Helm.
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McFadden, D. (1978). Modelling the choice of residential location in spatial interaction theory and planning models. In A. Karlquist, L. Lundquist, F. Snickars & J. W. Weibull (Eds.), Spatial interaction theory and planning models (pp. 75-96). Amsterdam: North-Holland. Meyer, R. (1980). A descriptive model of constrained residential search. Geographical Analysis, 12, 2 1-32. Michelson, W. (1979). Environmental choice, human behavior and residential satisfaction. New York: Oxford University. Murie, A. (1974). Household movement and housing choice. Birmingham, England: Center for Urban and Regional Studies. Palm, R. (1976). Real estate agents and geographical information. i7ze Geographical Review, 66, 266-280. Phipps, A. G. & Carter, J. E. (1984). An individual-level analysis of the stress-resistance model of household mobility. Geographical Analysis, 16, 176-189. Phipps, A. G., & Clark, W. A. V. (1988). Interactive recovery and validation of households' residential utility functions. In R. G. Golledge & H. J. P. Timmermans (Eds.), Behavioural modelling in geography and planning (pp. 245-27 1). London: Croom Helm. Phipps, A. G. & Laverty, W. J. (1983). Optimal stopping and residential search behavior. Geographical Analysis, 15, 187-204. Pollakoski, H. (1982). Urban housing markets and residential location. Lexington, MA: Lexington Books. Porell, F. W. (1982). Models of intraurban residential relocation. The Hague: Kluwer. Quigley, J. M. . (1983). Estimates of a more general model of consumer choice in the housing markets. In R. E. Grierson (Ed.), Ihe urban economy in housing (pp. 125-140). Lexington, MA: Lexington Books. Rossi, P. (1955). why families move. Glenco, IL: The Free Press. Schneider, C. H. P. (1975). Models of space searching in urban areas. Geographical Analysis, 7, 173-185. Slovic, P., Fischoff, B., & Lichtenstein, S. (1977). Behavioral decision theory. Annual Review of Psychology, 28, 1-39. Smith, T. R., Clark, W. A. V., Huff, J. O., & Shapiro, P. (1979). A decision making and search model for intraurban migration. Geographical Analysis, 1 1 , 1-22.
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Smith, T. R., Clark, W. A. V. & Onaka, J. (1982). Information provision: An analysis of newspaper real estate advertisements. In W. A. V. Clark (Ed.), Modelling housing market search (pp. 160-186). London: Croom Helm. Speare, A., Goldstein, S. & Frey, W. (1975). Residential mobility and migration and metropolitan change. Cambridge, MA: Ballinger. Timmermans, H. J . P. (1984). Decompositional multi-attribute preference models in spatial choice analysis.-Progress in Human Geography, 8, 189-221.
Weibull, J. W. (1978). A search model for microeconomic analysis with spatial application. In A. Karlquist, L. Lundquist, F. Snickars, & J. W. Weibull, (Eds.), Spatial interaction theory and planning models @p. 47-73). Amsterdam: North-Holland. Wrigley, N. (1985). Categorical data analysis. London: Longmans.
Behavior and Environment: Psychological and Geographical Approaches T. Garling and R.G. Golledge (Editors) 0 1993 Elsevier Science Publishers B.V. All rights reserved.
CHAPTER 12
Search and Choice in Urban Housing Markets W. A. V. Clark
Studies of residential search and choice now form a substantial and coherent body of knowledge (Clark, 1981, 1982a, 1982b, 1986). Methodological developments in discrete choice models (Wrigley, 1985), research in conjoint measurement (Phipps & Clark, 1987) and investigations of scaling models of choice (Timermans, 1984) continue to stimulate studies of search and choice at local and aggregate scales. It is not possible to do justice to the whole of this literature. The focus of this chapter is narrowed to studies which have explicitly incorporated the spatial context or a spatial structure into the research design. It is useful to examine what is still a reasonable structure for examining residential search choice questions and to place the more recent explicitly spatial contributions into that larger research context. The larger context is one in which the residential relocation process is divided into a decision to move, a decision to view alternatives (search), and the actual relocation behavior (the choice outcome itself). The decision to move is now accepted as a process of adjusting a (perceived) disequilibrium, sometime viewed as stress m u f f & Clark, 1978) but in every case a tradeoff between a current and an alternative residential location. The search process is driven by households falling out of adjustment and into disequilibrium as their housing composition changes. The search process is less clearly specified although there is a substantial body of empirical results which suggests a wide range of approaches to house search. The final choice is seen in the context of matching household needs to housing characteristics. (Figure 12.1) The investigations of search and choice in geography now have a two and a half decade history and the analytical and empirical contributions have provided a rich understanding of the dimensions of the search process (Clark 1981, 1983) However, as Montgomery notes (Chapter 13 of this book), we are still a good distance from being able to predict the
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likelihood of a move or the actual choice of a dwelling. The work that has been accomplished as sketched out in Figure 12.1 suggests a set of models which parallel the division of research into the likelihood of a move, the decision to search and the search process itself and the actual dwelling
MODELLING THE DYNAMICS OF SEARCH AND CHOICE DISEQUILIBRIUM MODELS OF THE LIKELIHOOD OF A MOVE I
V MODELS OF SEARCH
Decision to Search
4
MODELS OF INFORMATION
ACQUISITION AND USE
I
Relocation Behavior
FIGURE 12.1. The structure of research on search and choice in residential
mobility.
choice. The complexity involved in modelling choice and search has tended to generate research and models within one of these contexts and as yet there are no overarching models which truly link models of the decision to move and the search process. Hence it is better to think of the decision to move and the choice itself as the structure with the search process embedded within the overall mobility decision making. The multinomial hierarchical choice models (McFadden, 1978; Lerman, 1979; Lierop, 1981, 1986; Porell, 1982; Clark & Onaka 1985) have come closest to providing a decision making structure in which the choice to
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move is the primary choice, followed by the choice of area to search followed by the choice of house to select but empirical testing has been limited. Why Study Residential Search and Choice? For at least two decades the emphasis in behavioral studies of residential relocation was on why people moved and occasionally on the impacts of mobility on individuals and on the urban structure. Slowly, however, it became apparent that we needed to know much more about the complex interconnections between the urban structure and human behavior. It was no longer enough to show that people often moved short distances in neighborhoods that they were familiar with, that they moved to bring their housing consumption nearer to equilibrium consumption, that younger households moved more often or that tenure was important, (that renters moved more often and owners less often). It was important to relate mobility to the built environment and to ask questions about the interaction of search, choice, and impacts both on the changing neighborhoods of cities and, by extension, on the population composition of neighborhoods. The focus on mobility and choice for its own sake was replaced by a concern with the integration of the processes of search, choice, and urban structural change. The focus moved from studies of why people moved to what were the processes and impacts of population relocation. In turn it created a bipolar approach to understanding relocation behavior. Simple questions of why people move were replaced either with studies of the socio/psychological processes of decision making or studies of geographic outcomes. Understanding how people make decisions and understanding the choices that they make enriches our understanding of the general processes of behavior in the city and, by extension, our understanding of how neighborhoods change in the city. Just as studying activity patterns provides a way of assessing the relationship between environment and behavior, so studies of the search patterns and the choices that households make provides a link between the built environment, the neighborhoods of the city, and the people who live in them. Why do certain households end up in certain locations, and how are choices of locations affected by search and selection? These are questions which arise from a focus on residential search and choice when those topics are linked to the urban built environment.
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A concern with residential search and choice is more than a way of linking behavior and urban structure. It also allows us to raise important questions about how housing opportunities are known and used, and on the spatial extent of peoples' experiences of the built environment. Even more important, the search and relocation behaviors raise questions about the extent to which choices are exercised freely or are constrained by household factors and factors of the market. For a time investigations of residential migration emphasized household preferences and unconstrained choices (Clark, 1981; Rossi, 1955). A counterbalancing perspective (Murie, 1974; Barrett & Short, 1979) emphasized the constraints on the mobility process which arise from the structure of the housing market itself and the actions of institutional actors in the housing market. To some, the actions of individual households were better explained by the nature of the housing system than consumer preferences (Barrett & Short, 1979), to others the individual choice process was still the primary explanation (Clark, 1986). Now, most research takes a middle ground with the actions of individuals grounded in the structure of the housing market. While individual households are necessarily constrained by the availability of housing by tenure, price and location, at the same time there is considerable evidence of individual choices in both controlled and less controlled housing markets pieleman, Deurloo, & Clark, 1989), and that the same processes are at work in both controlled and uncontrolled markets pieleman et al., 1989). Even though there are still vigorous debates about choice and constraint, in the end studies of search and choice in the housing market will be important to the extent that they inform policy. While the extent of the spatial search for new housing is probably only peripherally related to questions of housing provision, a better understanding of the preferences for particular tenures, a better understanding of locational preferences and how those preferences are formed and how they influence choices in the housing market are an important part of understanding how the urban structure will evolve. Current interests in urban restructuring, in polycentric urban forms and the spatial organization of a pluralistic urban form will be better served by a theoretically informed understanding of residential search and choice.
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The State of Knowledge
To reiterate, initial studies of residential migration revolved around "why did a household move" and "who got what" in the housing market when they moved.The emphasis was on choice of tenure, choice of housing composition (size, amenities and so on) and choice of location. The studies were designed to explore the question of why people moved, and why they chose a given location and a given house. The research from this approach documented that people moved to improve their housing situation, to increase their space, to own rather than rent, and to improve their accessibility within their locational context. A quantitative evaluation of the choices emphasized the housing context as the explanation of their choice rather than the neighborhood or the environment. But even though this initial research has now provided a rich documentation and understanding of residential choices, and serviceable models of the way in which disequilibrium in housing consumption leads to the decision to move, the "moving process" itself was at least initially neglected. However, by the end of the decade of the ~ O S studies , of search had provided a set of new conceptualizations and documentation of the empirical nature of search. Implicit Spatial Models of Search There are two sources for much of the initial research on residential search and choice. On the one hand, marketing and economics provided basic models of "search", and, on the other hand, psychology focused on choosing among alternatives. While marketing has some similarities with the psychological approaches, economics built a strong theoretical approach to the process of "stopping search". Such models focus on the issue of when to accept an offer (usually a job offer), versus continuing to search and to incur the associated costs. The job search literature (Clark & Flowerdew, 1982) emphasizes the influence of information and the way in which uncertainty and the flow of information influence the decision to continue searching. As in other work by economists, the emphasis has been on the nature of optimum search strategies within utility-maximization frameworks (Phipps & Laverty, 1983). There have been attempts to frame housing search in this context (Ioannides, 1979). The large literature in psychology is more concerned with choice among alternatives (which of course implies the existence of a search and evaluation process).
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The emphasis in the psychological literature is on how alternatives are evaluated rather than how they are collected and identified. The focus extends to the role of information and opinion revision rather than identification. To psychologists, choice emphasizes individual judgments. These are often judgments of sets of alternatives conveyed to a panel and do not include identification of alternatives. The latter may be more central in the residential decision making environment. (For a discussion of the psychological approach, see Slovic, Fischoff, & Lichtenstein, 1977; Clark & Flowerdew, 1982.) Geographers borrowed from this work and evaluated the use of stopping rule models (Flowerdew, 1976) and disequilibrium approaches to residential mobility in general (Smith, Clark, Huff, & Shapiro, 1979). But, again as in the economic approaches, these models were only implicitly spatial and there was a tendency to treat space or location as simply one attribute of the alternatives to be considered. Even so, in the Smith et al. (1979) presentation, although space was implicit it was an important component of the model. The expected utility attached to search for a dwelling in ''a given neighborhood" is based upon the household's prior estimates of the housing characteristics in the area and the expected costs of search in that area (Smith et al., 1979). Thus, neighborhoods are clearly a part of the model but are the context in which search occurs rather than the defining characteristics of the process itself. These notions of the search process as a utility-equilibrium process emphasize that an individual's decision to search is a function of the difference between the expected utility of further search and the utility of the best vacancy found to date (Clark & Smith, 1982). As the model is neighborhood (or community) based, individuals compute the locational stress of neighborhoods in the city and search in the neighborhood which gives rise to the largest positive stress value, that is the neighborhood where the likelihood of success is greatest. A vacancy with greater utility than the current house (or vacancy) becomes the best alternative, and search continues until stress is driven to non-positive values in all neighborhoods. A test of the model in a section of Los Angeles provided some support for the process described by the model. Models of spatial reside& search. In contrast to the Clark/Smith equilibrium approach, Huff (1986) provided two classes of models which are truly spatial, focusing on the nature of selection from areas and in relationship to search constraints (Figure 12.2). The area-based search model is the outcome of considering the search process as one in which households make the decision to visit a particular vacancy conditional on
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the area containing that vacancy. Areas with large numbers of vacancies have a greater chance of being included in the search space. But at the same time the prior search experience of the household influences the likelihood of visiting particular areas. Selecting an area is followed by a more intensive activity in that area with high probabilities of visiting vacancies near the last vacancy visited. Huff (1986) provides a formalized model of these observations, and in a test of the model in a part of the Los Angeles region, shows that households tend to persist in submarket search once an area has been identified and "provides strong behavioral evidence of the existence of geographically defined submarkets that limit the domain of search for individual households" (Huff, 1986, p. 217).
FIGURE 12.2 The spatial context of search based on Huff (1986).
The anchor-points search model also assumes that the observed search pattern reflects the underlying distribution of vacancies. However, in this case the bias in the spatial pattern of search is related to locational preferences of the household and specifically of the way in which a household concentrates search in a small area around a focal point. Search declines in intensity around the focal point. The empirical basis for this model suggests that a subset of households employ a locationally persistent search strategy by which they concentrate effort near the mean center of the search pattern. That the anchor-points model was able to match the observed search distribution over 50% of the time is convincing evidence of the importance of anchor or reference points in the search process. Both the area-based and the anchor-point models provide evidence of the strong spatial regularities in residential search. These models demonstrate that it is possible to build operational search models which build space
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into the search process in such a way that we can predict where households will search and, by extension where they will move.
The Intersection of Search, Choice and the Housing Market Environment An important element of the Huff (1986) search models is the recognition of variation in the housing market. Housing markets are differentiated spatially. They are differentiated by tenure and by price, It is this differentiation which underlies the creation of residential environments which are reflected in the search and choice process of individual households. Households do not search and choose in a vacuum. They are able to segment the housing market by these important variables which then enter into the search and choice process (Bourne, 1981). A generally accepted view is that submarkets for housing do exist but at the same time there is only a limited literature devoted to defining their structure, and even less on the way in which these submarkets influence search and choice. Even so, some form of spatial segmentation is at the heart of the discussions that we have introduced in this chapter. There are clearly identifiable areas (by price, quality, accessibility, and so on), and it is these areas which help define the search process. Bourne (1981) has suggested that at the smallest spatial scale, the neighborhood scale, the only distinguishing feature of the housing market is that of limited spatial entity. Of course the difficulty is in defining that spatial entity. To date the definitions of submarkets are pragmatic statistical decisions and not theoretically based interpretations of the links between households and the housing stock. Beyond that we need additional studies of the links between the submarkets and the way they influence the search process. The models introduced by Huff (1986) are a beginning.
Empirical Observations on Search While the models have been developed to conceptualize the process of housing search there has been a number of studies designed to document the dimensions and characteristics of search. These empirical investigations have evaluated the length of search, the spatial extent of search, and the information used in the search process.
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Economists have identified these factors as measures of search effort and search costs. For geographers there has been an attempt to create a picture of the search activities of households. Another way of thinking of these factors is to think in terms of the dimensions that they represent. They are dimensions of time, (length of search; how may alternatives does a household view? and how long do they search before making a decision? what rules does the household use to make the decision?), space (the spatial pattern and extent of search; where does the household look?) and information (the nature and use of information in the search process) (Huff 1986). To some extent these dimensions have been discipline specific. Economists have focused on the issues of stopping, hence on issues of the length of search. Psychologists have emphasized the role of information processing, and geographers have been more concerned with empirical estimates of the spatial nature of the search. On each of these topics however, there is a substantial body of empirical information. Length of search. The surprising finding that housing search is a relatively short process still stands. Barrett (1973) in studies in Toronto, Canada and Hempel (1969) in Connecticut in the United States, pointed out that a third of all home buyers and half of all renters consider only one alternative. Clark (1982) found that recent home buyers in the Los Angeles area searched less than a month, within an area of about 3 miles radius, and looked at about 15 houses. Mackett and Johnson (1985) reported that three quarters of the searches by owners were completed in six months and half within three months. Of course, length of search and the number of units searched are closely related. An important part of the search for housing is the relationship with the urban environment and the necessity, despite recent telemarketing of houses, to visit neighborhoods and houses within neighborhoods. Measures of search intensity - houses visited, neighborhoods and communities searched, the distance of search and the length of search all confirm the limited time and narrow spatial context of search (Figure 12.3). The diagrams reported for Los Angeles in the figure can be replicated for other metropolitan areas and in other cultural contexts. They provide an important empirical basis for the area and anchor point search models designed by Huff (1986). There have been numerous suggested explanations for the relatively short search time. These hypotheses are drawn from economic approaches to search. Until now they have not been examined within psychological approaches to choice and decision making. The first explanation assumes
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that households are satisficers and are quite risk averse in their selection of alternative houses. Smith et al. (1979) suggested that the satisficing behavior leads households to stop search when they have found a unit with certain minimal conditions. A second explanation calls on the cost of search as a constraint in the search process. If we include within the cost of search the personal energy cost as well as foregone earnings and real dollar outlays for travel and other activities, this hypothesis can be a compelling explanation for the shortness of search especially when, in the case of renters the choices can be further modified within a relative short period of time. That renters search much shorter periods and examine fewer alternatives is direct evidence that households are aware of the search cost to returns ratio. Although some have suggested that data collection may not have identified all the alternatives and that prior to active search there may be a sifting of alternatives, this is less easily tested. Goodman (1976), in particular, has identified a series of testable propositions concerning the optimal length of search and the nature of the stopping rule employed by households given that the search model accurately describes search behavior. Three of the propositions may be directly related to the general explanations of limited search. If G is the
Search Intensity
Length of search (web)
Number of houses
Y
E
te
L
1
2
3
4
5
6
Number of areas
FIGURE 12.3 Distributions illustrating intensity.
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W. A. V. Clark
distribution of net gains to the household for all vacancies (or areas) in the domain of search (gains relative to the household's current living condition), then the following propositions should be true (Huff, 1982): 1) Given the known costs of search and the expected utility or net gain from search, there is some minimum net gain, g, such that any vacancy found with a net gain g greater than or equal to g will be selected even though further search might uncover a better alternative; 2) the greater the variance of the G distribution, the greater is the expected number of units searched; and 3) the lower the costs of search relative to the expected value of G, the greater is the expected number of units searched. Although there are no direct tests of the propositions, the available evidence offers general confirmation. If the gains are smaller and the distribution has less variance (rental units versus houses), then renters should search for shorter periods. This has been confirmed (Michelson, 1979; Rossi, 1955, Speare, Goldstein, & Frey, 1975). Meyer (1980) has shown that the size of the household's choice set is likely to be a function of the amount of variance which exists in the population of alternatives (Meyer, 1980). For proposition (3), the support seems to come in the main from studies of the search behaviors of low-income households. Their search behavior is constrained by resource limitations including poor access to private transportation (Cronin, 1982). They face higher search costs relative to the total resources available and hence curtail search. The spatial context of search. There is still only a small group of studies which have effectively measured the nature of search in and across residential neighborhood contexts. The approaches to spatial search have been divided by Huff (1986) into studies, first, which focus on the areas searched and more particularly on the number of housing units examined in a set of neighborhoods and, second, studies which identify a point pattern of houses and locations which are in the search space. In addition to these two conceptual approaches, prior empirical contributions have been largely descriptive. They provide detail on the more limited areal searches conducted by low income and minority households and more extensive search patterns of higher income households. The combination of a restricted set of vacancies available to low income and minority households, and the general likelihood of searching in familiar areas (especially for lower income households) explain the spatially biased patterns that emerge.
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The spatial context within which search occurs has also been of some concern to policy makers and especially those concerned with the increasing inner city suburban dichotomy. Deurloo, Clark, and Dieleman (1990) have provided evidence of the constrained nature of residentialrelocation behavior. The latter study showed how in The Netherlands household choices reflect their initial locations. Households relocate by making choices in residential environments very similar to those in which they originate, while owners (with generally higher incomes) can effect less constrained choices. In general, search and choice are constrained processes. Information and search and choice. It has long been established that the availability, amount, and quality of information have a direct influence on the nature of the choice process. Detailed information of relative prices and the prices of alternative units will enable the decision maker to make a more informed decision. However, while there is valuable data on information use in general (Table 12.1), the application or linking of information and residential search is still fragmentary. Most empirical studies have been concerned with the amounts and types of information available to searchers in the housing market, but even these studies have in the main provided only general information on the differences in information use by income. Barrett (1973) provides support for Rossi's (1955) observation that lower-income households rely more heavily on personalized information sources such as friends and family. Palm (1976) has shown that real estate agents spatially bias the information provided to searchers. Other studies stress the changing nature of the information source over time (MacLennan & Wood, 1982). As search proceeds, the importance of personal knowledge and the use of friends and relatives decline and newspapers increase in importance. In the later stage, general areal information is replaced with specific data on housing availability. Mackett and Johnson (1986) use survey data to show that ideas change during the search process, perhaps as the result of information processing. Several empirical studies focused on the relative roles of different sources of information. Sources varied from real estate and newspapers to signs, building contractors, and co-workers. But how are the sources used? What is the sequence of use? Although some information is provided by Clark and Smith (1979), the role and impact of information channels is still a largely unexplored area. Clark and Smith (1979) showed in a simulation study that searchers are sensitive to the cost of information and their search efficiency is significantly less with high cost information.
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Of some interest to realtors is the (not unexpected) result that good agents speed up the process of search. Other approaches focus on the provision of information rather than on its consumption. Such studies highlight another important dimension of trying to understand the process of search and choice. An analysis of real estate advertisements by both realtors and homeowners provides very different conceptions of the provision and use of information. In short, while both owners and realtors provided detailed price information (though fluctuating over time), in general owners provided much more exact location information than realtors. While realtors wish to take buyers to houses and to "sell houses", owners clearly wish to give buyers the opportunity for independent non-involved inspection (Smith, Clark, & Onaka, 1982). Of course, it is also more efficient for owners who need not show the house to every possible purchaser. The study was not able to provide definitive conclusions of the way in which information varied over time, but there was some evidence of changing information provision in stable and price escalating markets (Smith et al., 1982). TABLE 12.1
Relative Weighting of Information Sources Used in Housing Choice Source type
Citation
Real Estate
News- Relative/ paper friend
Walking/ riding around
Signs Contnctors
Did not search
Other ~
Rossi (1955) Hempel(1970) Barren (1973) Hehrt(1973) Spare (1975) Michelson (1977) Goodman(l978)
11 38 24 18 5 25 21
15 25 15 18 17 26 16
38 12 21 36 19 15 22
15 4
6
25 11 32 28
12 10
35
6 4
20 15 3 17 3
-_ 6
Finally, there is still only limited research on residential utility functions, yet such research may be central to understanding the way in which households choose particular dwellings. Moreover it is this research which brings closer links between the work of psychologists, geographers and economists. Phipps and Clark (1988) were able to document an adaptation process of residential preference formation which may account
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for some of the difficulty in generating models of the search and selection process. The work suggests that innate residential utilities of households are being modified by their experiences in their local housing markets. The interaction of preferences and the local housing market are a critical element of understanding search behavior.
New Directions: Where Do We Go From Here? Recent analyses of hierarchial search have been somewhat concerned with mathematical specificity rather than empirical evaluation and both these and previous works do not yet have an overarching organizing theme (Jayet, 1991). However, research on residential search and choice can be fitted into a developing theme which has been suggested as a way to view the processes of moving, locational and housing choice. Within the last decade the concern to develop a conceptual structure within which the notions of housing choice and residential mobility can be embedded has led to a focus on the housing career and the life course as approaches to understanding the complex interrelated activities of search and choice. Kendig (1984, 1990) used the notion of housing careers as an organizing principle to examine the intersection of housing choices and family composition. Kendig (1990) attempts to form a link between the housing tenure decision on the one hand and the family life cycle on the other. To do this, he suggests that housing careers are the means for linking mobility and the life cycle. In this sense he is building on the work of Michelson (1977) who suggested that households pass through a series of dwellings that increasingly meet their long term housing aspirations. The paths of individual households through the housing stock are influenced by broader social changes as well as life transitions and local housing markets. In this sense the notions of housing demography link the life course (path of the individual), the housing career (the housing units that the household occupies), and the social economic changes in the household itself. The life course is an even broader context in which the housing career can be situated. Mayer and Tuma (1990) have summarized the notion of the life course as a concept for viewing the progress of an individual or groups of individuals (or even institutions) through their lives. This process though life can be viewed as a sequence of events. The event list includes a wide range of occurrences from events related to education, to family formation, to career decisions, and not the least to housing and
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shelter decisions, in turn interrelated with the decisions about family and career. Much of the research in life course analysis has focussed on the individual life span and the way in which it is shaped and organized, not just by the decisions of individual actors but by the cultural beliefs of the individual and both the social and spatial context in which the individual is situated. The aim of life course analysis is to look at individual life events and the patterns of life trajectories (the terminology of housing careers is quite similar) in the context of the social processes that generate these events and trajectories. In the past there was much attention directed to the issue of spatial mobility as such and search behavior was simply an associated activity which might create greater understanding of the mobility process. Increasingly however, the focus is not on spatial mobility as such, nor on the relationship of search behavior as related to spatial mobility; rather the focus is on the analysis of the dynamics of the separation between work and residential locations. Search then becomes important to the extent that it provides an understanding of how work and residence relationships influence mobility and housing choice. New work will necessarily address the complexity of the decision making process in which spatial change both in the city and between regions is the process whereby households link work and residence and the processes of mobility, migration, and commuting are used to effect that linkage. The life course can be used to study the events and the timing between the events of the decisions to search, to move or commute, and/or to change jobs, as events in a trajectory of change over time. This conceptualization may provide the structure for a dynamic and interactive approach to choice and decision making in space.
References Barrett, F. (1973). Residential search behavior. (Geographical Monograph No. 1) Toronto, Canada: York University. Bourne, L. (1981). f i e geography of housing. London: Arnold. Brummel, A. C. (1979). A model of intraurban mobility. Economic Geography, 55, 338-352. Clark, W. A. V. (1981). On modelling search behavior. In D. Griffiths & R. McKinnon (Eds.), Dynamic spatial models (pp. 102-131). Alphen aan de Rijn, The Netherlands: Sijthoff and Noordhooff.
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Clark, W. A. V. (1982a). Modelling housing market search. London: Croom Helm. Clark, W. A. V. (1982b). Recent research on migration and mobility: A review and interpretation. Progress and Planning, 18, pp. 1-56. Clark, W. A. V. (1986). Human migration. Newbury Park, CA: Sage. Clark, W. A. V., & Flowerdew, R. (1982). A review of search models and their application to search in the housing market. In W. A. V. Clark (Ed.), Modelling housing market search (pp. 4-29). London: Croom Helm. Clark, W. A. V., & Onaka, J. (1985). An empirical test of a joint model of residential mobility and housing choice. Environment and Planning A , 17, 9 15-930. Clark, W. A. V., & Smith, T. R. (1979). Modelling information use in a spatial context. Annals of the Association of American Geographers,
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