A merger in vocational interest research: Applying Holland's theory to Strong's data

Journal of Vocational Behavior, 2, 353-376 (1972)

A Merger in Vocational Interest Research: Applying Holland’s Theory to Strong’s Data DAVID P. CAMPBELL1 University of Minnesota and JOHN L. HOLLAND Johns Hopkins University Six scales representing Holland’s six personality types-Realistic, Investigative, Artistic, Social, Enterprising, and Conventional-were developed for the SVIB. These were used to score 202 occupational samples from the Strong archives, and the mean scores for each sample on each scale are reported here. The ranking of means conform well with Holland’s theory. The highest mean scores were: Realistic: Machinists, tool and die makers, vocational agriculture teachers; Investigative: Physicists, chemists and psychologists; Artistic: Actors, artists, and interior decorators; Social: YMCA staff members, ministers, guidance counselors; Enterprising: Salesmen, department store managers, and buyers; Conventional: Bankers, business education teachers, and office workers. These scales are now available for research use.

This is a report of an attempt to integrate two streams of work in vocational interest measurement: E. K. Strong’s empiricism (Strong, 1943; Campbell, 1971) and John Holland’s theory (Holland, 1969). We have developed six scales for the Strong Vocational Interest Blank (SVIB) to represent Holland’s six types, and then used these scales to analyze the vast Strong archival data. This paper reports the techniques used, and the results. STRONG’S SYSTEM Early Research Strong is the acknowledged pioneer in the study of interests, and his major contribution was a stark, empirical approach at a time-the 1920’s and 1Requests for reprints should be directed to David P. Campbell, Center for Interest Measurement Research, University of Minnesota, Minneapolis, Minn. 55455.

353 Copyright @ 1972 by Academic Press, Inc. All rights of reproduction in any form reserved.

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30’s-when intuition ran rampant among psychologists. He chose to study vocational interests because he believed that data from the early studies of interest showed considerable promise for understanding occupational behavior. When he began, he was fully aware that he didn’t know much about what he was doing and, with what in retrospect appears to be a total absence of bias, he set out to fill the chasms of ignorance with hard data. When he died 40 years later (in 1963) he left behind, systematically filed, one of the largest collections of psychological data on adults in the world. To the end of his career, his approach was dominated by empiricism (see, for example, Strong, Campbell, Berdie, & Clark, 1964) and, although he developed many research strategies which had at least the status of working theories, he never attempted any global, simplifying, parsimonious theory. Strong’s general goal was the expansion of his data collection to answer specific questions. He worked mainly with occupational samples-usually with men or women over age 25-and he, and his successors, were always eager to add more samples as fast as the available resources permitted. He also devoted much of his time to gathering longitudinal data by following up students who had been tested years earlier. His technique was always very data orientedthough he was shrewdly intuitive in moving from one empirical step to the next-and his knowledge was slowly built up from his statistics. On the few occasions that he allowed himself to specuiate in print about the theoretical nature of interests, he was neither comfortable nor persuasive. (See, for example, Strong, 1958.) The Occupational Scales The major outcome of Strong’s work was the development of a large number of occupational scales, each with some demonstrated concurrent validity, i.e., the power to discriminate between the interests of men in a specified occupation and those of men-in-general. When possible, he also studied the predictive validity of these scales; here the results were also positive, although the level of accuracy was considerably lower than for the concurrent validation. Much normative work has also been done on these occupational scales, such as using them to score other samples of students and adults. The results were again positive in the sense that the data generally looked plausible (e.g., chemists scored high on the physicist’s scale and vice versa) but they highlighted the occasional idiosyncratic nature of empirical scalesidiosyncratic here means data that we do not understand or that do not conform to common sense, e.g., the finding that 50% of high school senior boys scored high on the (1938) Farmer scale. These established characteristics of the SVIB scales have significant features for the user. Because the scales are empirically sound and usually

STRONG-HOLLANDMERGER

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mesh well with one’s common sense, a fairly accurate, although superficial, interpretation is easy. To a student with a high score on the Physician scale,a counselor can say, “You have interests similar to physicians.” This interpretation is technically correct and, in many cases,practically useful-which is why the SVIB has continued so long in use. However, becausethe scalesare empirical and not satisfactorily tied into a theoretical framework, the user has an enormous conceptual burden. For precise interpretation, he must know all of the empirical studies of the individual scales, especially those highlighting their idiosyncrasies. For the Farmer scale, for example, he must know that a majority of all high school boys, urban as well as rural, score fairly high, and then he must use such data in modifying his individual interpretations. In general, the SVIB succeedswell in describing many trees, but the conceptual task of providing a map of this rich forest has not been well worked out. Although Strong made some attempts, such as arranging the scales on the profile to emphasize the relationships between them, the interpretive problems are still great. Complexity Analysis of the SVIB

Another feature of the SVIB complicates usage, and that is the complexity of analysis. Strong’s technique of isolating many atomistic differences between two samples requires a long inventory to provide enough differences for a stable scoring key. Then, because the individual’s answers have to be compared with the specific differences isolated for each scale, scoring is complicated and expensive.In practice, this createsdifficulties, both in cost and in time lag between test administration and scoring. Finally, Strong’s system is, to use Clark’s (1961) terminology, “open,” that is, scalescan be added indefinitely. Whenevera new occupation is tested, a new scale can be constructed. While this has certain advantages-it is always good to learn more about occupations-it leads to ever-increasing ponderousnessand diminishing returns. Once three or four scientific occupations are tested, for example, adding others in the same area becomesless informative. The proliferating number of scales,while valuable to the practitioner, is especially troublesome to the researcherwho wishes to use the SVIB profile to describehis sample; descriptive statistics reporting mean scoresfor 50 or 60 scalescan hardly be consideredefficient data reduction. HOLLAND’S SYSTEM The Development

Holland’s system, in contrast, is “closed,” that is, it has a set number of

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scales-six-to represent his major personality types: Realistic, Investigative, Artistic, Social, Enterprising, and Conventional. Their development has been describedearlier in “The Psychology of Vocational Choice,” (Holland, 1966): “The formulations for the types grew out of my experience as a vocational counselor and a clinician, and out of my construction of a personality inventory from interest materials. After reviewing the vocational literature-especially factor analytic studies of personality and vocational interests-I concluded that it might be useful to categorize people into six types.” (p. 15). “The present types are analogous in some ways to those proposed earlier by Adler, Fromm, Jung, Sheldon, and others. They differ from these earlier typologies in their origin-which is largely our vocational literatureand in their definitions. The six major factors identified in Guilford’s comprehensive factor analysis of human interest-mechanical, scientific, social welfare, clerical, business, and aesthetic-approximate the present types. To the best of my knowledge, Guilford’s factor analysis is the most explicit forerunner of the present typology.” (p. 10).

By concentrating on these types and developing a body of knowledge about each, Holland easesthe conceptual burden on the user, but demands more from him concerning specific interpretations. For example, if an individual scoreshigh on the Realistic scale, moderate on Social, and low on Enterprising, we know much about him, but to offer suggestionsas to what occupational niches he might seek, we need to know a great deal about individual occupations. With the Strong system, the counselor has many trees but a vague map, but with the Holland system the counselor has a map with only a few vague locations of individual trees. These characterizations of orientation are overdrawn, but they capture the main differences between these approachesto interest measurement.Now we must learn about Holland’s map. Holland’s Six Types Realistic. This type is masculine, physically strong, unsociable, and aggressive;has good motor coordination and skills; lacks verbal and interpersonal skills; prefers concrete to abstract problems; seeshimself as aggressive and masculine with conventional political and economic goals; rarely performs creatively in the arts or sciences. Such men prefer occupations such as mechanic, electrician, fish and wildlife specialist, crane operator, and tool

designer. Investigative. (Previously termed Intellectual). This category includes those who are task-oriented, introspective and asocial; prefer to think through rather than act out problems; have greater curiousity about the need to

STRONG-HOLLAND

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understand the physical world; enjoy ambiguous work tasks; prefer to work independently; have unconventional values and attitudes. These men tend to choose occupations such as astronomer, biologist, chemist, writer of technical articles, and zoologist. Artistic. The artistic model is asocial; avoids problems that are highly structured or require grossphysical skills; resemblesInvestigative type in being introspective and asocial but differs in having a greater need for individual expression, less ego strength; is more feminine and suffers more frequently from emotional disturbances; prefers dealing with problems through selfexpression in artistic media. Vocational preferences include artist, author, composer,writer, musician, dramatic coach, and symphony conductor. Social. This type is sociable, responsible,feminine, humanistic, religious, and needs attention; has verbal and interpersonal skills, avoids intellectual problem solving, physical exertion, and highly ordered activities; prefers to solve problems through feelings and interpersonal manipulation of others. Vocational preferences include clinical psychologist, missionary, high school teacher, marriage-counselor,and speechtherapist. Enterprising. This type has verbal skills for selling, dominating, and leading; seeshimself as a strong, masculineleader, avoids well-defined language or work situations requiring long periods of intellectual effort; differs from Conventional type in that he prefers ambiguous social tasks and has an even greater concern for power, status, and leadership; is orally aggressive.Chooses occupations such as: business executive, political campaign manager, real estate salesman,stock and bond salesman,and television producer. Conventional. Conventional men prefer structured verbal and numerical activities; are conformist and prefer subordinate roles; are effective at wellstructured tasks, but avoid ambiguous situations and problems involving interpersonal relationships and physical skills; identify with power; value material possessionsand status. Vocational preferencesinclude bank examiner, bookkeeper, financial analyst, quality control expert, statistician, and traffic manager. THE MERGER OF THE TWO SYSTEMS Scale Construction

The first step was to construct six scalesfor the SVIB to represent these six types. The actual technique used here might be called “informed, empirical, interative intuition.” Campbell, who had become convinced by studying item and scale clusters on the SVIB that Holland’s six types were useful for understanding the structure of interests, studied Holland’s descriptions of these types carefully, and selected a cluster of SVIB items to represent each.

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The first approximation was shown to Holland, each item on each scale was discussed, problems were identified, and a second approximation was prepared jointly. The two main problems were: (1) an unequal number of items were available for each type; and (2) some items cut across several different types. “Statistician,” for example, has elements of both Investigative and Conventional and “Stockbroker,” cuts across Enterprising and Conventional. This second approximation was looked at closely by both authors independently, and comments were again exchanged on specific items. When this round was finished, there were roughly 20 items for each scale. Twenty was thus selected as the goal, and each scale was tailored to exactly 20 items. All of this work used the item pool of the revised Strong form (Campbell, 1966), which meant that these scales could be used with the current SVIB, but could not be used with the Strong archival data which are based mainly on the 1938 form. Consequently, these scales were scanned to see how many new (1966) items were included; one scale had as many as six. These, of course, had to be eliminated from the scale before it could be used with the older booklets. To retain a common number of items, six items were dropped from each of the other five scales. The resulting 14 item scales (Set I) can be used with any form of the Men’s SVIB ever published; the 20 item scales (Set 11) can be used only with the 1966 booklet (T399). Whenever possible, the Set II scales should be used because they are longer and slightly. more reliable. After applying the raw-score to standard-score conversion described below, scores from the two sets can be compared directly. In some preliminary work, we had contemplated using only raw scores, with some type of interpreted output, and the tables of data in the Appendix of the SVIB Handbook (Campbell, 1971) use that system. As we moved further on, the advantages of standard scores once again became evidentmainly in making comparisons across scales-and we have switched to standard scores. The final scales, both Set I and Set II, are listed in Table 1. The items are scored by weighting the responses as follows: Like, +l; Indifferent, 0; Dislike, - 1. Thus the raw scores for each scale range from +20 to -20. Because this scale-building technique depended on intuition-the early Minnesota empiricists would have, in unkindly tones, labeled it “armchair psychology”-we are likely to be criticized by our more statistically-oriented colleagues. In anticipation of this, we emphasize the following points: (1) The intuition was well-informed. Both authors have had several years of experience in working with the items from interest inventories, including inspecting their response percentages in various samples, their intercorrelations, and their individual idiosyncrasies. (2) Further, the psychometric characteristics of the resulting scales were studied carefully; these findings constitute the remainder of this paper.

STRONG-HOLLAND

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(3) We did pay attention to a number of specific considerations in item selection: (a) The items had to be related to one, but only one, of the Holland types, i.e., we wanted factorial purity. This was difficult to achieve, for factorial purity in items is not the natural state. (b) The items, as much as possible, had to be occupationally oriented. We wanted to take advantage of the powerful stereotypes provided by occupational titles and activities. (c) The items had to be clear and straightforward, with no ambiguity. (d) We wanted items spread throughout the range of popularity, except for the extremes. The MIG response percentages were examined for each item, and no items showing extremely high popularity or unpopularity were used. (e) We wanted items that were valid in discriminating between occupational groups; consequently, in general, those items most useful in constructing the SVIB occupational scales were used. The item composition of the scales is listed in Table 1; following is a brief summary of item content: Realistic: The items on this scale center around outdoor and mechanical activities, most of which involve little formal education. Investigative: This scale is dominated by science items. Artistic: These items deal with artistic and musical activities, including sketching, sculpting, photography, cartooning, and dramatics. Social: These items mostly involve service to others-the ministry, teaching, working with youth. Enterprising: These items deal primarily with sales and the direct management of business. Conventional: These items are concerned with office work, low level accounting, and the organization of business activities. When we originally began, we had hoped to develop scales that could be used as absolute measures, without norms and without conversion to standard scores or percentiles. As the scales were equal in length, we anticipated that a simple count of the “Like” responses would provide a useful score. That has not worked out. The main problem is that the items in some scales are more popular than the items in other scales. For example, among the SVIB Men-In-General sample (N=lOOO), the raw score means range from 5.53 on the Investigative scale down to -2.86 on the Enterprising scale, over 8 raw score points, which is roughly equivalent to one raw score standard deviation. Obviously, a raw score of +5 on the Investigative scale means something different than the same score on the Enterprising scale. To overcome such disparities, and to make comparisons across scales easier, the Men-In-General sample has been used as a normative sample; their means and standard deviations-reported in Table 2-are used in the usual T-score conversion formula, and all scores can now be compared to the normative sample’s mean of 50 and SD of 10. These data, along with the L-I-D scoring weights of +l, 0, - 1 for the items in Table 1, can be used by other investigators who wish to score other SVIBs with these scales. Table 2

Item

Military officer Auto racer Auto mechanic Airplane pilot Building contractor Carpenter Civil engineer Farmer Locomotive engineer Rancher Shop foreman Tool maker Agriculture Industrial arts Mechanical drawing Hunting Pop. mech. magazines Cabinetmaking Operating machinery Be Forest Ranger

4* 12 13 14 17 19* 24 37 55 76 88 94 102 121* 122 139* 1t30* 189 190 214*

Realistic

Item number 3 6 10 23 34* 45 64* 69 a3 93* 106 107 108 120 125” 128 129 144 212 264*

Item number Architect Astronomer Author tech. book Chemist Geologist Inventor Psychologist Physician Sci. research worker Surgeon Botany Calculus Chemistry Mathematics Nature study Physics Psychology Chess Do research work Outstanding scientists

Item

Intellectual

1 5 9 20 30* 43 46* 62 66 71 84 104 110 141* 163 172 183* 233 261* 263*

Item number

Item Composition of the Holland Scalesa

TABLE 1

Actor Artist Author of novel Cartoonist Art museum director Interior decorator Photographer Musician Orchestra conductor Poet Sculptor Art Dramatics Sketch pictures of animals Art galleries Poetry Magazines about art and music Look at toll. of antique furniture Musical geniuses Prominent artists

Item

Artistic

228 251*

209

202 203

89 100 133 161* 164* 169* 184 192 196

82

59* IO

26 33

I*

Athletic Director Minister, priest, rabbi Employment manager High school principal Playground director School teacher Social worker Worker in YMCA Sociology Go to church Leading Boy Scouts Church youth group Sot. problem movies Give “first aid” asst. Interview men for job Teaching children Teaching adults Adjust difficulties Contribute to charity Babies

Item

238* 243* 245

219

211*

90 92* 95* 99 197 201

80 81 85

17

18 42 54

s* 11

Item number Auctioneer Auto salesman Buy merchandise Hotel manager Life ins. salesman Real estate salesman Retailer Sales manager Manager, cham. of comm. Specialty salesman Stockbroker Traveling salesman Wholesaler Interviewing people Start conversation Bargaining (swapping) Buying merchandise Aggressive people People assume ldrship. Made fortune in business

Item

Enterprising

QItems marked with an asterisk were eliminated from Set I scales.

Item number

Social

111* 208* 223 224 226* 221 241 210*

91* 103 105 111 134 135

21 25 36* 65 14

15

Item number Bank teller Cashier in bank City or State employee Income tax accountant Office manager Private secretary Statistician Arithmetic Bookkeeping Economics Spelling Typewriting Bus. methods magazines Make statistical charts Methodical work Regular hours for work Developing bus. systems Saving money Thrifty people Insist on things in proper place

Item

Conventional

CAMPBELLAND HOLLAND

362

TABLE 2 Meansand StandardDeviationsfor Normativeand Correlation Sampleson the SVIB-Holland Scales Normative samplea (raw scores) N=1000 Set II Mean SD

Set I Mean SD

Set II Mean SD

0.71 6.38

1.73

8.69

46.85

46.36

3.87

5.53

8.26

53.29

1.59

9.65 8.11

56.64 54.84

8.90 6.94

49.83 49.90 10.87

Set I Mean SD

Scale Realistic Investigative Artistic Social Enterprising Conventional

Correlation sample (standardscores) N=150

6.32

1.06 7.23 1.64 5.93 -2.64 6.89 0.30

4.81

2.22 -2.86 -0.86

10.67

9.40 9.27 9.97 8.98

53.95 56.72

10.79 9.07 9.41

54.29 10.16 49.36 8.89 49.55 10.06

QThenormative sample,by definition, has a StandardScoremeanof 50 and SD of 10 on each scale.

TABLE 3 SVIB-Holland ScaleIntercorreIations (Set II Scales) R Realistic Investigative Artistic Social Enterprising Conventional

.980

I .39 .98

A

S

.09

.18

.23

.13 .34

.98

.97

E

C

.33 -.08 -.03 .38

.36 .14 -.04 .25 .52

.97

.94

aCorrelationsin diagonalare between same-namedSet I and Set II scales.

also contains the means and SDS for the sample used to generate scale intercorrelations. The scale intercorrelations-reported in Table 3-were derived from a sample of 150 men and women. This sample, which is used frequently at Minnesota to generate correlations because each individual filled out both the Men’s and Women’s form, was collected by approaching a psychology graduate-level class-not al! future psychologists, but a majority-and asking them to ask their friends and family to fill in both forms, emphasizing that we wished diversity. We succeeded only moderately on the latter point, as can be seen from their means in Table 2; the sample, about half students, scored

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much higher on the Investigative and Artistic scales than on the Enterprising and Conventional scales. The raw score standard deviations for these scales in this sample were roughly 6.0 for the Set I (14 item) scales and 8.0 for the Set II (20 item) scales. The scale intercorrelations were generally low with two or three exceptions, the main one being the correlation of 0.52 between the Enterprising and Conventional scales. This correlation might be slightly inflated because of the particular sample used here, as these students may have indiscriminately rejected both of these areas. Such an interpretation is also supported by the relatively low correlation between the Investigative and Artistic scales. This sample, which scored highest on these two scales, may have made subtler discriminations in these two areas, as compared with their responses to the items on the Enterprising and Conventional scales. In general, the scales that correlated with each other are located next to each other, and the ordering corresponds to that suggested in earlier Holland reports. The correlations in the diagonal are between the same-named Set I and II scales, e.g., between Realistic I and Realistic II. These correlations are quite high and the results from the two sets, when modified appropriately, can be used interchangeably when practical considerations demand this. Some might argue that because the correlations are so high, the shorter scales should be used for simplicity, yet we prefer the longer scales, both because they are more reliable, and because they provide more variance (standard deviations of 8 versus 6) to work with. However, practical considerations dictate the use of shorter Set I scales when working with the older form of the SVIB, as explained above, and these high correlations do permit interchangeable interpretations of the two sets of scales. Mean Scores for Diverse Occupational Samples Whenever new psychological scales are built, they should be submitted to rigorous analysis, using data from samples other than those used in the scale construction; this is especially true when the scale construction methods depend on subjectivity (as all scale construction methods are to some extent subjective, all new scales should be checked against external samples). The most important check on these scales was to use them to score all of the occupational samples in the SVIB data archives, and this of course was one of the important goals of this project-to see how the Strong samples would arrange themselves on the Holland dimensions. (Johansson, 1971, has reported on how various groups of students score on these scales.) For this purpose, 202 samples were used, with a median sample size of about 250. The mean scores for these samples are reported in Tables 4-9.

41

48

49

50

51

52

53

54

60 59 58 51 56 55

Standard score

Machinists/tool & die makers/voc ag teachers Skilled tradesmen/highway patrolmen/electricians/farmers (1968)lcarpenters (1969)/policemen (1968) Foresters/farmers (1967)/policemen (1969) Air Force officers/carpenters (1936)/pilots Ag ext agents/engineers (1968)lpurchasing agents (1969)/Army officers (1950) Astronauts/cartographers/farmers (1936)/Generals & Admirals/neurological surgeons/physical therapists (1966)/forest service men/petroleum engineers Math-sci teachers (1968)/radiologists/vets (1966)/NASA scientists/urologists/Army officers (1969)/food scientists/Navy officers/physical therapists (1957) Elementary teachers (NoDak)/No Hennipin Jr Co11stu/U of M fresh (1967)/va schizophrenic patients/U of M fresh (1966)/computer programmers/dentists/medical techs/chiropractors/vets (1949)/animal husbandry profs Architects (1968)ldental cd/dentists and dental ed (1969)/dept store mgrs/salesmen, real estate(l969)/corp pres (1965)/ engineers (1928)/policemen (1933)/physiatrists/physicians (1969)/Colonels MIG (1966)/optometrists/pediatricians/school supers (1969)/comm ret direcs/salesmen, computer/biologists/public admins (194l)lcredit mgrs/legislators/production mgrs/salesmen, steel/sot sci teachers (1969)/salesmen, PG&E/math-sci teachers (1936)/printers Bankers (1934)/hankers (1964)/ministers (1969)/psychologists (exp)/salesmen, 3M/elementary teachers (Minn)/chemists (193l)/funeral direcs (1969)/CPA (1944)/chemists (1969)/ county welfare workers/osteopaths/Ferris State stu/ pathologists/personnel direcs (1927)/personnel direcs (1969)/salesmen, 3M applicants/YMCA PD/YMCA staff/business ed teachers/sales mgrs (1968) Bankers (1969)/physicians (1949)/public admins (1969)/social workers (1967)/dentists(l932)/English teachers/physicists (1927)/psychiatrists (1949)/psychologists (industrial) Musicians (1969)/physicists (1968)/salesmen, auto/salesmen, life insurance (1969)/CPA (1965)/MIG (1933)/ministers (1927)/U of M fresh (1964)/architects (1933)/governors/music teachers (1946)/priest (1966)/psychologists (market)/purchasing agents (193l)/ministers (1965)/school supers (1965)social workers (1953)/psychiatrists (1967)/ teaching brothers/guidance counselors (1950)/accountants/Cham Comm execs/funeral direcs (1945)/office workers/ psychologists (1949) Intemistslrehab counselors/YMCA sets/astronomers/buyers (1969)/Unitarian ministers (1950)/college profs/lawyers (1969)/photographers/psychologists (ed)/salesmen, Encyclopedia/advertising men (1968)/physicians (1927)/sot sci

Mean Scores for 202 Samples on the Holland Realistic Scale

TABLE 4

55

56

60 59 58

Standard Score

43 42 41 40 39

44

45

46

Physicists (1927)/chemists (1969)/psychologists (exp)/neurological surgeons/psychologists (statistical) Astronomers/biologists/pathologists/physicists (1968)/chemists (1931) surgeons/ (1949)/urologists/NASA scientists/pediatricians/internists/orthopedic Physicians (1969)/psychiatrists astronauts/psychologists (educ)/physiatrists/medical techs/psychologists (1949)/psychologists (industrial)/psychologist (1947)/psychologists (social)/mathematicians (1929)/psychologists (clinical/surgeons/psychiatrists (1967)/Air Force officers/radiologists/Math-sci (guidance)/mathematicians (1969)/dental cd/animal teachers (1968)/psychologists ,husbandry profslmath-sci teachers (1936)/psychologists (child) Engineers (1928)/machinists/physicians (1949)/engineers (1968)/food scientists/computer programmers/optometrists/ psychologists (market) Danforth fellows/college profs/physical therapists (1957)/physical therapists (1966)/psychologists (1967)/anthropologists/salesmen, computer/U of M fresh (1967)/economists/Army officers (1950)/petroleum engineers

Mean Scores for 202 Samples on the Holland Investigative Scale

TABLE 5

teachers (1936)/carp pres (1935)/guidance counselors (1968)/psychologrsts (chud)/psycnologsts (statistical)/musrcrans (1952)/judges and lawyers Buyers (1946)/psychologists (1947)/psychologists (clinical)/psychologists (guidance)/investment Mgrs/ Mpls Symphony/ sales mgrs (1932)/buyers for emporium/interpreters/sociologists/judges/salesmen, real estate (1932)/anthropologists/ mathematicians (1969)/German med students Football coaches/music teachers (1952)/school supers (193O)/mathematicians (1929)/pharmacists (1947)/student personnel workers/artists (1968)lbusiness admin profs/librarians/psychologists (1967)/economists Actors (1966)/lawyers (1949)/salesmen, life insurance (1966)/artists (1933)/Unitarian ministers (1929)/actors (1937)/ newsmen/psychologists (social)/CPA owners/interior decorators/salesmen, life insurance (1931) Danforth fellows/lawyers (1927) Advertising men (193l)/political scientists/Pulitzer prize winners Authors NIAL members/psychologists (German) Accountants (German)

$

b

c

:

I

45 44 43 42 41

46

41

48

49

50

51

52

53

54

5 (Continued) Investigative

Scale

Farmers (1968)

Cartographers/dentists/physicians (1927)/dentists and dental ed (1969)/U of M fresh (1966)/German med students/ pharmacists (1968) CPA (1944)/Generals and Admirals/Navy officers/elementary teachers (Minn/osteopaths/pilots/Mpls Symphony/ policemen (1968)/Army officers (1969)/chiropractors/dentists (1932)/student personnel workers/foresters/sociologists Architects (1968)/rehab counselors/business admin profs/psychologists (German)/pharmacists (1947)larchitects (1933)/public admin (1941)/LJnitarian ministers (1950)/Generals & Lt Generals/librarians/ministers (1969)/Unitarian ministers (1929)/tool& die makers/CPA owners/NIAL members/vets (1966)/YMCA PD/school supers (1930) CPA (1965)/Colonels/carp pres (1965)/football coaches/credit mgrslelementary teachers (NoDak)/guidance counselors (1950)/forest service men/electricians/interpreters/ministers (1927)/personnel directors (1927)/policemen (1969)/ ag ext agents/production mgrs/school supers (1965) School supers (1969)/guidance counselors (1968)/ musicians (1952)/photographers/accountants/County Welfare workers/ patrolmen/judges/policemen MIG (1966)/public admins (1969)/social workers (1953)/ voc ag teachers/highway (1933)/skilled tradesmen/artists (1968)/investment mgrs/political scientists/priests/social workers (1967)/comm ret direcs/musicians (1969)/vets (1949)/actors (1966)/carp pres (1935)/purchasing agents (1969)/salesmen, 3M/salesmen, PG&E/teaching brothers Judges and lawyers/artists (1933)/YMCA staff/office workers/business ed teachers/ministers (1965)/music teachers (1946)/salesmen, steel/YMCA sets/buyers for emporium/farmers (1936)/lawyers (1949)/MIG (1933)/U of M fresh (1964)/dept store mgrs/personnel direcs (1969)/Cham Comm execs/lawyers (1969)/high school counselors/legislators/ printers/music teachers (1952)/sales, 3M applicants Actors (1937)/carpenters (1936)/Pulitzer Prize winners/bankers (1964)/lawyers (1927)/sales mgrs (1932)/salesmen, auto/County Sheriffs/English teachers/purchasing agents (1931) Advertising men (1968)lArmy sergeants/salesmen, Encyclopedia/sales mgrs (1968)/VA schizophrenic patients/advertising men (193l)/funeral direcs (1969)/governors/accountants (German)/soc sci teachers (1969) Bankers (1969)/newsmen/sot sci teachers (1969)/buyers (1969)/funeral direcs (1945)/salesmen, life insurance (1966)/carpenters (1969)/authors/salesmen, life insurance (193l)/salesmen, real estate (1969)/buyers (1946) No Hennepin Jr Co11 stu/salesmen, life insurance (1969)/Ferris State stu/bankers (1934) Interior decorators/salesmen, real estate (1932) Farmers (1967)

Mean Scores for 202 Samples on the Holland

TABLE

8 F $ CJ

z

F

g

49

50

51

53 52

54

55

64 63 62 61 60 59 58 57 56

Standard Score

Artistic

Scale

Actors (1937) Artists (1968) Interior decorators/NIAL members Mpls Symphony/Danforth Fellows/photographers Architects (1968)/Pulitzer Prize winners/Unitarian ministers (1950)/artists (1933) Music teachers (1952)/advertising men (1968) Architects (1933)/ministers (1965)/English teachers/librarians/musicians (1952)/musicians (1969)/Unitarian ministers (1929)/anthropologists teachers (1946)/psychologists (1967)/college profs/neurological Newsmen/psychiatrists (1967)/ ministers (1927)/music surgeons/physiatrists/psychologists (1947)/elementary teachers (Minn) (clinical)/political scientists/ministers (1969)/ sociologists/astronomers/authors/judges/physicians Psychologists (1969)/social workers (1953)/economists/physicists (1968)/dental educators/interpreters Psychiatrists (1949)/psychologists (social)/advertising men (193l)/priests (1966)/social workers (1967) German med students/psychologists (exp)/teaching brothers/pediatricians/personnel direcs (1927)/student personnel workers/judges & lawyers/psychologists (ed)/psychologists (child)/orthopedic surgeons/psychologists (1949) (guidance)/YMCA sets/mathematicians Biologists/chemists (1969)/elementary teachers (NoDak)/psychologists (1969)/psychologists (German)/public admins (1969)/salesmen, Encyclopedia/lawyers (1969)/dentists/psychologists (industrial)/business admin profs/Cham Comm execs/comm ret direcs/salesmen, 3M/salesmen, 3M applicants/dentists and dental educators (1969)/investment mgrs/guidance counselors (1968) Personnel direcs (1969)/computer programmers/physical therapists (1957)/radiologists/YMCA staff/chiropractors/ football coaches/internists/pathologists/policemen (1968)/psychologists (market)/YMCA PD/NASA scientists/medical techslsalesmen, life insurance (1966)/surgeons/urologists Astronauts/dentists (1932)/physicians (1949)/ sot sci teachers (1936)/ag ext agents/business ed teachers/optometrists/ rehab counselors/physical therapists (1966)/school supers (1965)/cartographers/legislators/guidance counselors (1950)/mathematicians (1929)lpublic admins (194l)/math-sci teachers (1968)/psychologists (statistical)/school supers (1930)/food scientists/Army officers (1950)/buyers (1969)/MIG (1966)/printers/salesmen, computer/VA schizophrenic

Actors (1966)

6

Mean Scores for 202 Samples on the Holland

TABLE

63 62 61 60

Standard Score

44 43 42 41

45

46

47

48

6 (Continued) Artistic

Scale

YMCA secretaries/ministers (1965)/rehab counselors/social workers High school counselors/YMCA PD/guidance counselors (1968)

YMCA staff

7 Social Scale

(1953)/guidance

Mean Scores for 202 Samples on the Holland

TABLE

counselors (1950)

Engineers (1968)/Generals & Admirals/math-sci teachers (1936)/school supers (1969)/salesmen, PC&E/buyers for emporium/county welfare workers/credit mgrs/physicists (1927)/sot sci teachers (1969)/lawyers (1927)/lawyers (1949)/dept store mgrs/osteopaths/physicians (1927)/sales mgrs (1968)/salesmen, steel/MIG (1933)/Navy officers/office workers/policemen (1969)/U of M fresh (1964) life insurance (193l)/pharmacists (1968)/purchasing agents/carpenters Foresters/governors/machinists/salesmen, (1936)/chemists (193l)/funeral direcs (1969)/CPA (1944)/carp pres (1965)/Colonels/engineers (1928)/high school counselors Animal husbandry profs/pllots/policemen (1933)/sales mgrs (1932)/Army officers (1969)/tool & die makers/core pres (1935)/U of M fresh (1966)/Army sergeants/bankers (1969)/funeral direcs (1945)/Forest Service men/petroleum engineers/salesmen, auto/salesmen, life insurance (1969)/CPA (1965)/production mgrs/U of M fresh (1967)/highway patrolmen County Sheriffs/salesmen, real estate (1932)/salesmen, real estate (1969)/skilled tradesmen/Generals & Lt Generals/Vets (1964)/purchasing agents (1931) (1966)/pharmacists (1947)/electricians/carpenters (1969)/f armers (1936)/hankers Bankers (1934)/voc ag teachers/North Hennepin Jr Coll stu/vets (1949) Accountants (German)/Ferris State students Farmers (1967) Farmers (1968)

Mean Scores for 202 Samples on the Holland

TABLE

8 F

E t is

z

FE

46

41

48

49

50

51

52

53

55 54

56

51

58

59

Ministers (1969)/Unitarian ministers (195O)/soc sci teachers (1969)/ministers (1927)/student personnel workers/social workers (1967) School supers (1965)/school supers (1969)/comm ret direcs/soc sci teachers (1936)/elementary teachers (NoDak)/ policemen (1968)lpriests (1966) Ag ext agents/teaching brothers/bus ed teachers/physical therapists (1957)/psychologists (guidance)/salesmen, 3M applicants/elementary teachers (Minn)/legislators/county welfare workers Psychologists (1947)/dept store mgrs/personnel direcs (1969)/school supers (1930)/physical therapists (1966)/salesmen, 3M/salesmen, Encyclopedia/music teachers (1952) English teachers/voc ag teachers/psychologists (Ed) Math-sci teachers (1968)/physiatrists/Danforth Fellows/math-sci teachers (1936)/psychologists (clinical)/footbaB coaches/sociologists County Sheriffs/Cham Comm execs/credit mgrs/VA schizophrenic patients/public admins (1969)/Unitarian ministers (1929)/medical techs/salesmen, life insurance (1969)/chiropractors/highway patrolmen/psychiatrists (1949)/psychiatrists (1967)/psychologists (child)/music teachers (1946)/personnel direcs (1927)/salesmen, life insurance (1966) Pediatricians/pharmacists (1968)/salesmen, steel/policemen (1969)/funeral direcs (1969)/psychologists (market)/sales mgrs (1968) Judges/physicians (1969)/purchasing agents (1969)/psychologists (1967)/Jibrarians/psychologists (1949)/governors/ psychologists (industrial)/psychologists (social)/public admins (1941)/Army officers (1969)/machinists/psychologists (German)/vets (1966)/buyers (1969)/optometrists Generals & Lt Generals/lawyers (1969)/Army sergeants/lawyers (1949)/dental educators/interpreters/salesmen, computer/judges and lawyers/animal husbandry profs/salesmen, real estate (1969)/Air Force officers/policemen (1933)/cartographers/salesmen, PG&E Advertising men (1968)/Colonels/foresters/orthopedic surgeons/osteopaths/salesmen, life insurance (1931)/bus admin profs/CPA (1965)/dentists and dental ed (1969)/food scientists/internists Bankers (1964)/buyers for emporium/Mpls Symphony/musicians (1952)/musicians (1969)/pharmacists (1947)/psychologists (statist.)/urologists/college profs/buyers (1946)/Generals & Admirals/Navy officers/newsmen/political scientists/ tool & die makers/dentists/vets (1949)/astronauts/office workers/salesmen, auto/accountants/electricians/skiJJed tradesmen/biologists/computer programmers/German med students/neurological surgeons/physicians (1949)/surgeons/engineers (1968)lactors (1966)/chemists (1969)/funeral direcs (1945)/MIG (1966) Radiologists/Nasa scientists/forest service men/Army officers (1950)/CPA (1944)/ economists/carp pres (1965)/production mgrs/psychologists (exp)/bankers (1969)/farmers (1968)/MIG (1933)/pathologists/U of M fresh (1964)/CPA owners/carpenters (1969)/petroleum engineers/No Hennepin Jr COB stu Printers/sales mgrs (1932)/interior decorators/investment mgrs

k+ \o

I5 z? g

E

F

2 g 3 g

54

64 63 62 61 60 59 58 57 56 55

Standard score

43 42 41 40

44

45

7 (Continued) Social Scale

8 Scale

Salesmen, 3M, applicants/salesmen, 3M Dept store mgrs/sales mgrs (1968)/salesmen, life insurance (1969) Salesmen, Encyclopedia/salesmen, PC&E Salesmen, real estate (1969) Salesmen, auto/salesmen, computer/buyers (1946)/buyers (1969) Business ed teachers/elementary teachers (Minn)/salesmen, life insurance (1966)/buyers for emporium Policemen (1968)/credit mgrs/funeral direcs (1969)/purchasing agents (1969)/salesmen, life insurance (1931 .) Pharmacists (1968)/YMCA secs/Cham Comm execs/sales mgrs (1932)/salesmen, real estate (1932) Funeral direct (1945)/legislators/pharmacists (1947) sci teachers Personnel directors (1969)/county welfare workers/voc ag teachers/guidance counselors (195O)/soc (1969)/comm ret directors/office workers Ag ext agents/VA schizophrenic patients/purchasing agents (193l)/rehab counselors/YMCA staff/chiropractors/high school counselors/school supers (1965)/school supers (1969)/advertising men (1968)/food scientists/policemen (1969)/osvcholoaists (market)/soc sci teachers (1936)

Mean Scores for 202 Samples on the Holland Enterprising

TABLE

Astronomers/lawyers (1927)/actors (1937)/hankers (1934)/carpenters (1936)/carp pres (1935)/Ferris State stulmathematicians (1929)/architects (1968)/physicians (1927)/farmers (1936)/farmers (1967)/physicists (1968)/photographers/ salesmen, real estate (1932)/U of M fresh (1967)/Pulitzer Prize winners Dentists (1932)/U of M fresh (1966)/chemists (193l)/mathematicians (1969)/purchasing agents (193l)/advertising men (193l)/pilots German accountants/physicists (1927)/engineers (1928)/anthropologists/artists (1968) NIAL members/architects (1933) Authors Artists (1933)

Mean Scores for 202 Samples on the Holland

TABLE

20

43 42 41 40 39

44

45

46

41

48

49

50

51

52

53

Bankers (1969)/Army sergeants/guidance counselors (1968)/elementary teachers (NoDak)/county sheriffs/highway patrolmen/Air Force officers/Army officers (1969)/hankers (1964)/No Hennepin Jr Coll stu/ministers (1969)/vets (1966) Machinists/YMCA PD/bankers (1934)/CPA (1965)/football coaches/carp pres (1935)linterior decorators/public admins (1969) Governors/physical therapists (1966)/accountants/ctographers/optometnnel directors (1927)/petroleum engineers/farmers (1968)/advertising men (1931)/Ferris State stu/social workers (1953)/tool & die makers/carpenters (1969)/investment mgrs/MIG (1966)/Navy officers/skilled tradesmen Music teachers (1952)/carp pres (1965)/electricians/engineers (1968)/physical therapists (1957)/MIG (1933)/production mgrs/U of M fresh (1964)/vets (1949)/Army officers (195O)/English teachers/farmers (1967)/foresters/math-sci teachers (1936)/lawyers (1969)lmusic teachers (1946)/CPA (1944)/medical techs/ministers (1965)/policemen (1933) Colonels/farmers (1936)/carpenters (1936)/musicians (1969)/public admins (1941)/Generals & Admirals/business admin profs/computer programmers/ministers (1927)/physiatrists/priests (1966)/school supers (193O)/social workers (1967)/animal husbandry profs/dentists/psychologists (industrial)/lawyers (1949)/osteopaths/dentists & dental ed (1969)/math-sci teachers (1968)/urologists/printers/psychologists (guidance)/student personnel workers,QJnitarian ministers (1950) Astronauts/judges and lawyers/orthopedic surgeons/U of M fresh (1967)/teaching brothers/internists/forest servicemen/ pilots/radiologists/CPA owners/musicians (1952)/physicians (1969) Dentists (1932)/hbrarians/psychologists (1947)/Generals and Lt Generals/psychologists (ed)/U of M fresh (1966)/psychiatrists (1967) Salesmen, steel/dental educators/psychiatrists (1949)/architects (1968)/neurological surgeons/pediatricians/judges/ physicians (1949)/psychologists (1967)/surgeons/NASA scientists Sociologists/chemists (193l)/lawyers (1927)/newsmen/psychologists (1949)/engineers (1928)/psychologists (statistical)/ chemists (1969)/economists (cBnical)/internists/photographers College profs/Mpls Symphony/architects (1933)/Unitarian ministers (1929)/biologists/psychologists (chiid)/physicians (1927). Actors (1966)/political scientists/pathologists/psychologists (exp) Danforth Fellows/psychologists (social)/astronomers/mathematicians (1929)/mathematicians (1969)/actors (1937) Artists (1968)/authors/Pulitzer Prize winners/accountants (German)/physicists (1968)lphysicists (1927)/artists (1933) Anthropologists/German medical students Psychologists (German)/NIAL members z 2 ;a

$

g F

2 g z ‘?

50

51

52

54 53

55

62 61 60 59 58 57 56

Standard score

Bankers (1934)/business ed teachers Bankers (1964) Office workers/accountants/policemen (1968) County welfare workers Credit mgrs/soc sci teachers (1936) CPA (1944)/hankers (1969)/Colonels/dept store mgrs/elementary teachers (NoDak)/Army sergeants Guidance counselors (1950)/schooi supers (193O)/voc ag teachers/math-sci teachers (1936)/rehab counselors/policemen (1933) Purchasing agents (1931)&h school counselors/purchasing agents (1969)/school supers (1969)/CPA (1965)/YMCA sets/CPA owners/guidance counselors (1968)/school supers (1965)/printers/cartographers/public admins (194l)/public admins (1969)/ag ext agents/carpenters (1936)/pharmacists (1968)/accountants (German)/funeral direcs (1969)/ governors Legislators/librarians/medical techs/Army officers (1969)/buyers (1969)/ comm ret direcs/ministers (1927)/YMCA PD Buyers for emporium/funeral direcs (1945)/Generals & Admirals/mathematicians (1929)/VA schizophrenic patients/vets (1966)/Generals and Lt Generals/forest service men/salesmen, PG&E/farmers (1936) Business admin profs/music teachers (1952)/salesmen, 3M/MIG (1933)/personnel direcs (1927)/production mgrs/ pharmacists (1947)/sot sci teachers (1969)/U of M fresh (1964)/highway patrolmen/farmers (1967)/salesmen, real estate (1969)/Air Force officers/Army officers (1950)/personnel direcs (1969)/salesmen, auto/foresters/physical therapists (1957)/sales mgrs (1932)/salesmen, 3M applicants/salesmen, life insurance (193 l)/salesmen, life insurance (1969)/Cham comm execs/tool & die makers/vets (1949)/YMCA staff/elementary teachers (Minn)/farmers (1968)/Ferris State students/physiatrists/animal husbandry profs/county sheriffs/ministers (1969)/buyers (1946)/chiropractors/computer programmers/corporation pres (1935)/lawyers (1949)/machinists/optometrists/social workers (1953)/ministers (1965) Navy officers/petroleum engineers/policemen (1969)/psychologists (guidance)/MIG (1966)/math-sci teachers (1968)/ music teachers (1946)/physical therapists (1966)/salesmen, real estate (1932)/dentists (1932)/economists/electricians/ osteopaths/radiologists/skilled tradesmen/salesmen, steel Lawyers (1969)/psychologists (educ)/sociologists/U of M fresh (1966)/urologists/chemists (193l)/personnel workers/ teaching brothers/food scientists/judges and lawyers/salesmen, Encyclopedia/carp pres (1965)/engineers (1968)/

Mean Scores for 202 Samples on the Holland Conventional Scale

TABLE 9

3

z F

$

E

P 2E

L: h)

46 45 44 43 42 41 40 39

41

48

49

Artists (1933) Actors (1966)lartists (1968)

psychologists (1947)/U of M fresh (1967)/carpenters (1969)/No Hennepin Jr Coil stu/physicists (1927)/judges/priests/ English teachers/musicians (1969)/dentists/dentists and dental ed (1969)/investment mgrs Biologists/pilots/dental cd/neurological surgeons/orthopedic surgeons/psychiatrists (1949)/pathologists/physicians (1969)/psychologists (1949)/psychologists (child)/psychologists (social)/sales mgrs (1968)/Unitarian ministers (1929) Social workers (1967)/NASA scientists/Unitarian ministers (1950)/chemists (1969)/musicians (1952)/physicians (1949)/psychologists (market)/coBege profs/political scientists/salesmen, life insurance (1966) Physicians (1927)/salesmen, computer/internists/psychologists (exp)/psychologists (1967)/astronomers/psychologists (industrial)/surgeons/mathematicians (clinical)/architects (1968)/interpreters/psychiatrists (1967)/psychologists (1969)/physicists (1968)/Mpls Symphony/advertising men (1931) Architects (1933)/advertising men (1968)/astronauts/interior decorators Newsmen/Pulitzer Prize winners Authors/Danforth Fellows NIAL members/psychologists (German)/actors (1937)/anthropologists Photographers/German medical students

374

CAMPBELLANDHOLLAND

More information on each sample is in Campbell (1971); usually the short title used in the tables here is an adequateidentification. (The one exception, NIAL, standsfor membersof the National Institute for Arts and Letters.) If the Holland typology is useful, and if the scale development here has been successful, then two results should emerge from the tables of means: First, the means should arrange themselvesin a reasonablemanner, that is, to conform to common sense;and second, the meansshould be distributed over a wide enough range so that the differences between occupations.have some practical impact. Both of these trends are present. Listed below are the high- and low-scoring samples on each scale. The ordering is reasonable, especially among the high scoring samples-curiously, our common senseworks better in predicting high scores than low ones-and the range of meansextends over two standard deviations, not as great as the range of means on the SVIB Occupational scales, but clearly enough to conclude that the scales are spreadingoccupations apart.

Scale

High

Low

Realistic

Machinists R Tool & Die Makers R Voc. Ag. Teachers R

Political Scientists S Artists A Writers A

Investigative

Physicists I Chemists r Psychologists J

Farmers -R Interior Decorators A Salesmen E

Artistic

Actors A Artists A Interior Decorators A

Farmers R Bankers C Voc. Ag. Teachers R

Social

YMCA Staff S Ministers S Counselors S

Artists A Writers A Architects +$

Enterprising

Salesmen E Dept. Store Managers E Buyers E

Artists A Anthropologists I Physicists L

Conventional

Bankers C Bus. Ed. Teachers C Office Workers C

Artists A Actors A Photographers 4

STRONGHOLLANDMERGER

375

Without exception, the occupations with the highest mean scoresbelong to the appropriate Holland category. The letter following each occupation shows the Holland classification, see Holland, Viernstein, Kuo, Karweit, & Blum (1970), for classification details. The two systemsclassified all of them identically. In addition, some of the occupations with the lowest mean scores are opposites, i.e., across the diagonal, of the corresponding highest scoring occupations as classified by Holland’s hexagonal model (Holland, Whitney, Cole, & Richards, 1969). For example, Conventional occupations should be opposed to Investigative occupations, and Realistic should be opposed to Social. Clearly, the results show that the Holland theoretical structure, when applied to the Strong data, provides a useful model for organizing the data. Using the Results

There are three types of scalesnow for the SVIB-the original Occupational scales,the Basic Interest scales,and the Holland scales.The differences between the three are important and likely to be confusing. An analogy, using physical characteristics,might be helpful in explaining the differences. If one were classifying men by physical types, three kinds of statements might be useful: First, a gross classification, “He is tall and lanky,” or “He is short and wiry.” From such a brief categorization, a general picture of the individual is possible, and this is the function of the Holland scales-to give an overall pattern of the individual’s interests. Second, some measurementsof specific attributes, such as “He is 5 ft 10 in. and weighs 165 lb,” or “He has a reach of 40 in.” This is the function of the Basic Interest scales-to provide measuresof specific areasof interests. Third, some empirical statements about how this particular physique corresponds to those of men in various settings, “He is similar in build to jockeys,” or “He is built more like a halfback than a tackle.” This is the purpose of the Occupational scales. Each of these types of scaleshas unique advantagesand disadvantages. The Holland scales are parsimonious and give a general picture, the Basic Interest scales are homogeneous and provide measures of the strength in specific areas of interest, the Occupational scales offer an immediate tie between the individual’s pattern of interests and those of men in specified occupations. Is this much complexity necessary?Must we have three types? The answer is not clear, but if we don’t have them, users will dredge up such information out of their heads. No matter what kind of scalescoresthey are given-theoretical, homogeneous,empirical-practitioners tend to organize their interpretations in these three ways-general categories,underlying dimensions, and empirical tie-ins to the occupational world. In most instances,the clinical

376

CAMPBELL AND HOLLAND

generalizationsdrawn by the user will be less accurate than the analytic ones furnished by the system. Generalizations from specific facts and interpretations of patterns are better left in the hands of the computer, leaving the counselor free to help the individual understand his particular results and mesh them with his unique queries and requirements. The next step is to gain some clinical experience with these scales,to determine how they might best be used in practice.

REFERENCES Campbell, D. P. Manual for the Strong Vocational Interest Blank for men and women. Stanford: Stanford University Press, 1966. Campbell, D. P., Borgen, F. H., Eastes, S. H., Johansson, C. B., & Peterson, R. A. A set of basic interest scales for the Strong Vocational Interest Blank for men. Journal of Applied Psychology, 1968, 52, Part II. Campbell, D. P. Handbook for the Strong Vocational Interest Blank. Stanford: Stanford University Press, 197 1. Clark, K. E. Vocational interests of non-professional men. Minneapolis: University of Minnesota Press, 1961. Holland, J. L. The psychology of vocational choice: A theory of personality types and model environments. Waltham: Blaisdell Press, 1966. Holland, J. L., Whitney, D. R., Cole, N. S., & Richards, J. M., Jr. An empirical occupational classification derived from a theory of personality and intended for practice and research. ACT Research Report No. 29. Iowa City, Iowa: The American College Testing Program, 1969. Holland, J. L., Viernstein, M. C., Kuo, H. M., Karweit, N. L., & Blum, Z. D. A psychological classification of occupations Center for the Study of Social Organization of Schools Report No. 90. The Johns Hopkins University, 1970. Johansson, C. B. Cognitive interest styles of students. Journal of Measurement and Evaluation in Guidance, 1971, 4, 176-184. Strong, E. K., Jr. Vocational interests of men and women. Stanford: Stanford University Press, 1943. Strong, E. K., Jr. Satisfaction and interests. American Psychologist, 1958, 13, 449-456. Strong, E. K., Jr., Campbell, D. P., Berdie, R. F., & Clark, K. E. Proposed scoring changes for the Strong Vocational Interest Blank. Journal of Applied Psychology, 1964, 48, 75-80. Received: December 6, 1971