Valuing psychological factors in the provision of assisted reproductive techniques using the economic instrument of willingness to pay

Journal of Economic Psychology 19 (1998) 179±204

Valuing psychological factors in the provision of assisted reproductive techniques using the economic instrument of willingness to pay Mandy Ryan

1

Health Economics Research Unit, Department of Public Health, University Medical Buildings, University of Aberdeen, Foresterhill, Aberdeen AB9 2ZD, Scotland, UK Received 12 October 1996; received in revised form 10 March 1997; accepted 20 April 1997

Abstract To date economic evaluations of Assisted Reproductive Techniques (ARTs) have assumed that the only bene®t from the provision of such services is whether users leave the service with a child. Such studies ignore possible psychological outcomes resulting from going through ARTs. This study attempted to take account of the (dis)utility from such psychological outcomes, using the economic instrument of willingness to pay (WTP). WTP was estimated separately for those providing an ex ante and ex post evaluation. 307 respondents provided data on both their psychological states and feelings and their maximum WTP for ARTs. 229 of these respondents provided an ex ante evaluation and 78 an ex post evaluation. Psychological outcomes were found to be signi®cant predictors of WTP for both groups, with evidence being presented that the psychological feelings of regret and disappointment may be major motivators for individuals seeking ARTs. It is concluded that future evaluations of the service should take psychological outcomes into account, and WTP is potentially a useful economic instrument for doing so. Ó 1998 Elsevier Science B.V. All rights reserved. PsycINFO classi®cation: 3920 JEL classi®cation: C21; C42; C52; D12

1

Tel.: 01224 681818 ext 54965; fax: 01224 662994; e-mail: [email protected].

0167-4870/98/$19.00 Ó 1998 Elsevier Science B.V. All rights reserved. PII S 0 1 6 7 - 4 8 7 0 ( 9 8 ) 0 0 0 0 3 - 8

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M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

Keywords: Willingness to pay; Assisted reproductive techniques

1. Introduction To date economic evaluations which have attempted to inform the debate about the provision of Assisted Reproductive Techniques (ARTs) have assumed that the only factor that is important to users is whether they leave the service with a child. That is they have estimated a cost per live birth, cost per maternity or cost per some other narrow medical de®nition of success (Bartels, 1987; Batman, 1988; Page, 1989a; Wagner and St Clair, 1989; de Wit and Banta, 1991; Haan, 1991; Neumann et al., 1994). The implicit assumption here is that having a child is the only relevant argument in the infertile person's utility function, and, following on from this, that the only people who bene®t from (indeed are a€ected by) the provision of ARTs are those individuals who undergo treatment and leave the service with a baby. Whilst it is recognised here that the main objective of ARTs may be to help users conceive, this does not imply that such an argument has a monopoly in the infertile person's utility function. The very nature of the treatment may result in users experiencing psychological outcomes that would not be experienced if they did not go through treatment. This paper considers whether psychological outcomes enter the infertile person's utility function, using the economic instrument of willingness to pay (WTP). In Sections 2 and 3 information is provided on ARTs and current economic evaluations of In Vitro Fertilization (IVF). In Section 4 the rationale for using the economic instrument of WTP to assess arguments in the infertile person's utility function is discussed, and the WTP technique is described. Empirical work is then presented, showing the application of the WTP technique to measuring the psychological outcomes following going through ARTs. The methodology and results are presented in Sections 5 and 6. These results are discussed and conclusions reached in Section 7.

2. What are assisted reproductive techniques? ARTs are designed to help infertile individuals to conceive. Infertility has been de®ned as the failure to conceive after one year of regular sexual intercourse without contraception (Tietze, 1968). It is estimated that between 20%

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

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and 35% of couples will experience infertility at some point in their reproductive lives (Page, 1989b). Drug treatment is the most common form of treatment for the infertile. Surgical techniques are used to repair blocked fallopian tubes. The term ARTs usually refers to more advanced treatments of infertility, such as IVF and Gamete Intra Fallopian Transfer (GIFT). IVF involves extracting a ripe egg from the ovary, fertilising it with a sperm in a plastic dish and replacing it in the womb. GIFT di€ers from IVF in one respect ± the developed eggs, rather than being fertilised in a plastic dish, are transferred to the fallopian tubes, together with a concentration of sperm.

3. Current economic evaluations of ARTs To date economic evaluation of ARTs has implicitly assumed that having a child is the only relevant argument in the infertile person's utility function (Bartels, 1987; Batman, 1988; Page, 1989b; Wagner and St Clair, 1989; Webb and Holman, 1990; de Wit and Banta, 1991; Haan, 1991 Neumann et al., 1994). For example, Page (1989a) suggests that the e€ectiveness of IVF can be measured in terms of the number of couples treated, the number of maternities (a maternity may involve more than one baby) or the number of babies (which will be greater than the number of maternities). Haan (1991), in considering the eciency of IVF, suggests that: `the costs of the IVF treatment have to be related to the e€ects. The ultimate wanted e€ect from an IVF treatment is (at least) one liveborn baby'. Ratcli€e (1994), in a review of economic evaluations of IVF in Australia, comments: `the bene®ts of IVF treatment are almost always presented in the same format, the number of live births as a percentage of the total number of treatment cycles'. A similar assumption was made by Neumann et al. (1994) in their attempt to estimate the cost of a `successful' IVF delivery: `The key question... is not how much we spend on IVF but what is gained from the investment. In other words, what is the cost of a successful outcome of IVF'?

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Economic evaluations of ARTs have clearly assumed that the only factor important to users is whether they leave the service with a child. There is no justi®cation for this assumption in standard economic theory, within which the value of a risky good, such as ARTs, is the expected utility of the treatment viewed ex ante. This utility may include all sorts of psychological bene®ts; that is, economics provides no reason to view certain classes of bene®ts as unacceptable for the purpose of utility assessment. Research from the non-economic literature suggests that psychological feelings such as anxiety and stress may be provoked when going through ARTs. Stress and anxiety may result from such things as the cost of treatment (Nero et al., 1987), and the various critical points in the cycle (e.g. ultrasound following drug stimulation) (Seibel and Levin, 1987; Green®eld et al., 1988), egg retrieval (Kentenich et al., 1986; Dennerstein and Morse, 1985) and, if a pregnancy results, whether this will carry through to a maternity (Kentenich et al., 1986; Dennerstein and Morse, 1985) and, if so, the quality of this maternity (Dennerstein and Morse, 1985). There may also be stress and anxiety related to users' concerns about how the community views ARTs (Dennerstein and Morse, 1985), the rate at which the technology will proceed (Nero et al., 1987), and the potential side e€ects of treatment (Kentenich et al., 1986). In addition to this, users of the service may experience some psychological bene®t from knowing they have done everything possible to have a child (Zoeten et al., 1987; Holmes and Tymstra, 1987; Tymstra, 1989) Against this, there may also be some dis-bene®t from the disappointment of leaving the service childless, especially if the individual expected to leave the service with a child. 4. Willingness to pay: A method for considering psychological outcomes? One economic instrument that may allow the researcher to go beyond some narrow medical de®nition of success, and take account of such psychological outcomes in the infertile person's utility function, is WTP. This technique is based on the premise that the maximum amount of money an individual is willing to pay for a commodity is an indicator of the value to him/her of that commodity: `Political economy has to take as the measure of utility of an object the maximum sacri®ce which each consumer would be willing to make in order to acquire the object... the only real utility is what people are willing to pay' (Dupuit, 1844).

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The most obvious market where WTP behaviour is revealed is in auctions. Here individuals are pushed to consider the maximum amount of money they are willing to pay for a given commodity. When deciding on maximum WTP, they take account of the characteristics or attributes of the commodity that are important to them. For example, in a housing auction the individual will consider such characteristics as number of rooms, location, whether centrally heated, whether double glazed and house type. Given that individuals are held to consider all the attributes that are important to them in the provision of a good or service when placing a monetary value on it, WTP was felt to be appropriate when considering the value of ARTs. Davis (1963) proposed the use of survey data to estimate WTP in the absence of markets. Such surveys are commonly called contingent valuation (CV) surveys. Whilst these have been widely used to assess the utility of environmental goods (for a review of the application of CV in environmental economics see Mitchell and Carson (1989)), their use in health economics to date is limited (for a review of the application of CV in health economics see Donaldson (1993)). CV studies have used a number of techniques to assess maximum WTP, or utility, from hypothetical data. The four main ones are open-ended; bidding and payment card; and the closed ended (CE) or referendum technique. For a review of these techniques see Mitchell and Carson (1989) and Donaldson (1993). The CE approach has been recommended in the environmental literature since it is held to more accurately re¯ect the decision that individuals make every day i.e. individuals are presented with a cost, consider the attributes of the good or service, and decide whether or not they want to purchase it (Arrow et al., 1993). Whilst the questions may more accurately re¯ect the decisions individuals make every day, mean WTP is relatively more dicult to estimate and the approach requires a larger sample size than alternative WTP techniques to ensure accurate estimation of WTP. Estimation of WTP using the CE approach can be modelled within the framework of random utility theory (RUT) (Hanemann, 1984). This involves estimating the probability that an individual will say `yes' to any given bid amount. Using logistic regression techniques, the predicted probability of saying `yes' is: P ˆ …1 ‡ eÿ…a‡b:Bid† †ÿ 1;

…1†

where a + b. Bid is the estimated regression logit equation (when only the bid amount is included as an independent variable) and P is the probability of accepting the bid. Mean WTP is estimated as the area under this probability

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function. This area shows the proportion of the population who would consume the good at each price level, and their associated utility. This area can be estimated by integration techniques and can be expressed as ZU E…WTP† ˆ

…1 ‡ e L

ÿa‡b bid ÿ1

ZO

† db ÿ

1 ÿ …1 ‡ eÿa‡b bid †ÿ1 db;

…2†

L

ÿa‡b bid ÿ1

where …1 ‡ e † is the probability of saying `yes' and U and L the upper and lower limits of the integration, respectively. Assuming that individuals will not use the health care intervention if they receive a disutility from it, negative WTP can be ruled out and zero used as the lower limit. Bishop and Heberlein (1979) and Sellar et al. (1985) used the upper range of their bid amounts as the upper limit for the integration. Hanemann (1984) argued that such an approach makes assumptions about the probability distribution for the unknown (censored) WTP in the sample. He suggested that the upper limit should be in®nity. 5. Methods 5.1. Subjects and setting A pilot questionnaire, covering letter and stamped addressed envelope were mailed to a random sample of 116 individuals who had been through IVF treatment at Aberdeen's Assisted Reproduction Unit (ARU) since its opening in 1989 (GIFT was not available at this clinic). One aim of this pilot was to conduct an open-ended WTP study to establish the distribution of WTP responses which might then be used to establish the bid vector for the main closed-ended WTP study (more will be said on the closed-ended WTP approach below) (Cooper, 1993). The pilot also aimed to test the acceptability of all questions being asked of respondents. The main questionnaire was mailed to the remaining 1048 individuals (i.e. all minus the 116 in the pilot) who had undergone IVF treatment at Aberdeen's Assisted Reproductive Unit (ARU). Two reminders were sent. Given that the values of men and women may vary, and to prevent one partner from being dominant in completing the questionnaire, questionnaires were sent separately to men and women. Analysis was carried out to test whether views of men and women di€ered, using regression techniques (see Section 5.4 for more details). The data was also examined to establish wheth-

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185

er partners responses were `consistent' with each other. Given the nature of the data this was tested for as follows: all partners were grouped and their responses were then compared. Where partners both answered `yes' or `no' these responses were de®ned as `consistent' with each other. Where one partner answered `yes' and the other `no' these were de®ned as `consistent' if the `yes' was a response to a value lower than the `no' response and `inconsistent' if the `no' response was to a value lower than the `yes' response. 5.2. Psychological outcomes Following discussions with a psychologist who has worked in the area of infertility, two established scales were used to assess the psychological state of respondents: the Satisfaction with Life Scale (SWLS) (Diener et al., 1985) and the Positive A€ect Negative A€ect Scale (PANAS) (Watson and Clark, 1988). Using SWLS, individuals are presented with a list of ®ve statements about how they might be feeling. These statements are presented in Table 1. Using a Likert 1±7 scale, respondents are asked to indicate their level of agreement with each statement. A total score, which is the sum of the individual responses, is estimated for each individual, and can take on a value between 5 and 35, with a higher score re¯ecting more satisfaction with life. Missing values are set equal to the series mean. Using PANAS, Positive A€ect is concerned with `the extent to which a person feels enthusiastic, active and alert and Negative A€ect' is a general diTable 1 Responses to satisfaction with life scale (SWLS) Statement

In most ways my life is close to ideal The conditions of my life are excellent I am satis®ed with my life So far I have attained the important things I want in my life If I could live my life over again, I would change almost nothing

Strongly disagree

Strongly Non reagree sponses

Number of responses

1 6

2 65

3 67

4 62

5 6 83 137

7 43

3

463

8

47

62

57

111 143

36

2

464

5 19

43 71

52 76

56 42

81 179 98 122

48 36

2 2

464 464

37

84

83

56

68 109

25

4

462

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M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

mension of subjective distress'. Both Positive A€ects and Negative A€ects are measured on a 10 item scale (see Table 2). The 10 items measuring Positive A€ect are: interested, alert, inspired, determined, attentive, active, excited, strong, enthusiastic, and proud. The 10 items measuring Negative A€ect are: irritable, ashamed, nervous, jittery, distressed, upset, guilty, scared, hostile, and afraid. Respondents are asked to what extent they have felt each of the items during the last few weeks. Answers are recorded on a 1±5 scale, where 1 represents very slightly or not at all, 2 a little, 3 moderately, 4 quite a bit and 5 extremely. A total score ranging from 10 to 50 for both PANAS +ve and PANAS )ve emerges by summing the scores on the individual items. Missing values are again set equal to the series mean. Having devised total scores on the TSWL and PANAS, the t-test was used to determine whether there was any signi®cant di€erence in responses according to whether or not the respondent had a child from IVF treatment. In addition to these established psychological scales, attitude statements were presented to examine: whether users felt they would get some bene®t from going through the service even if they left it childless (`Even if we leave (or left) the IVF programme childless, I believe I will be (am) glad we tried it'.); whether there would be some bene®t from knowing you have tried everything possible to have a child (`One of the reasons we are trying (or tried) IVF is so that in later life I will know that we have tried everything possible to have a child'.); and the potential disbene®t from expecting to leave the service with a child, and then leaving it childless (`When we started the IVF programme I was very sure we would leave it with a child' and `When our ®rst Table 2 Responses to the positive and negative a€ect scale (PANAS) Positive adjective

n

Interested Excited Strong Enthusiastic Proud Alert Inspired Determined Attentive Active

448 451 449 448 449 445 446 447 446 447

Total score

466

Mean

Standard deviation

Negative adjective

n

Mean

Standard deviation

3.73 3.04 3.06 3.35 2.97 3.31 2.49 3.5 1.80 3.46

0.95 1.17 1.01 1.07 1.36 0.98 1.17 1.12 1.11 1.10

Distressed Upset Guilty Scared Hostile Irritable Ashamed Nervous Jittery Afraid

450 450 447 448 448 449 446 446 446 446

1.96 2.19 1.59 1.73 1.65 2.60 1.29 2.13 1.80 1.78

1.09 1.21 1.03 1.07 0.96 1.18 0.73 1.21 1.11 1.07

32.24

7.20

466

18.72

7.20

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

187

attempt at IVF failed I was surprised'.) (See Table 3.) Respondents were presented with these statements and asked to state their level of agreement along a Likert Scale from 1 to 7 where 1 represents strongly disagree and 7 strongly agree. The Mann±Whitney U test was used to determine if responses to these statements were related to whether or not the respondent has a child from the IVF/GIFT programme. 5.3. Willingness to pay question A recent report by Arrow et al. (1993) made numerous recommendations for the use of the WTP technique. An attempt was made to follow these guidelines where it was both possible and relevant. Following recommendations from this report, the closed-ended (CE) WTP approach was used. As suggested by the guidelines from the report, each individual received one discrete choice question in which they were presented with a speci®ed bid amount and asked whether they would have been prepared to go through IVF at this bid. The bid vector for the study was designed using a computer package devised by Cooper (1993). (The bid vector refers to the actual bids included in the study, and the number of respondents sent each bid amount.) Following recommendations from Arrow et al., a copy of the wording of the WTP question is shown in Appendix A. A copy of the bid vector is shown in Appendix B. One of the recommendations of the Arrow et al. report was that respondents must be provided with an accurate description of the program or policy being evaluated. Given that the respondents in this survey were actual users of the service, such a description was not necessary. Another recommendation was that respondents must be reminded of the opportunity cost of their expenditure. To allow for this, respondents were told Remember that any money you spend on IVF will not be available for you to spend on other things. Following the recommendations, a space was also provided for respondents to give a reason for their WTP response. Given that undergoing treatment involves uncertainty, respondents were not asked their WTP for completed treatment cycles since any such monetary valuation would have been based on the certainty of a particular result (and it may be argued that policy decisions should be based on ex ante rather than ex post valuations since it is ex ante that policy makers have to allocate scarce health care resources). Individuals who were currently undergoing treatment were asked their maximum WTP for that particular attempt (since at the time they would not know the ®nal outcome). If they were not undergoing treatment at the time but were willing to have another attempt, they were asked the

17

8 95 104

Strongly disagree 10

3 39 40

Statement

One of the reasons we are trying (or tried) IVF is so that in later life I will know that we have tried everything possible to have a child Even if we leave (or left) the IVF programme childless, I believe I will be (am) glad we tried it When we started the IVF programme I was very sure that we would leave it with a child When our ®rst attempt at IVF failed I was surprised

Table 3 Response to attitude statements

33

49

4

1

49

99

15

23

51

64

26

22

50

66

181

140

16

44

220

245

Strongly agree

123

10

9

8

Non responses

343

456

457

458

Number of responses

188 M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

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189

maximum amount they would be willing to pay for their next attempt. However, if they were neither going through treatment at the time, nor were willing to have another attempt, it was felt unrealistic to ask them their WTP for a further attempt. Given this, they were asked their maximum WTP for their last attempt. Given this, WTP was established from two di€erent groups: those who were valuing the service ex ante (the former two groups) and those who were valuing it ex post (the latter group). Two di€erent welfare measures were therefore being extrapolated ± the ex ante group provide a measure of compensating variation (cv) and the ex post group a measure of equivalent variation (ev). Compensating variation is the change in money income that is necessary to keep the individual at her initial level of utility (i.e. before they have an attempt at IVF) and ev the change in money income that is necessary to keep the individual at her ®nal utility level (i.e. after they have had an attempt at IVF). 5.4. Regression analysis Separate logistic regression models were estimated for the ex ante and ex post groups. To measure the importance of psychological factors in the provision of ARTs, responses to the SWLS, the PANAS and the attitude statements were included as independent variables in the logistic regression equation. Sex was included to test if the responses of women and men were similar. Other independent variables, which it was hypothesised, a priori, would in¯uence WTP, were also included in the logistic regression equation. Table 4 summarises them. For more information see Ryan (1995). A general to speci®c logistic regression method was used, with explanatory variables being excluded from the general model in a stepwise fashion (Norusis, 1990). A decision regarding the optimal functional form of the logistic regression model had to be made. Hanemann (1984) has argued that including the log of the bid as an explanatory variable is inconsistent with economic theory since the model cannot be derived from any explicit utility function. He also suggested however that such a model provides a good approximation for utility. It has been shown elsewhere that the log model provides a better ®t for the data (Sellar et al., 1986; Bowker and Stoll, 1988; Boyle and Bishop, 1988; Johannesson et al., 1991). In this study the linear and log-linear models were compared on the basis of their goodness of ®t i.e. the value of the loglikelihood function (with a value nearer to zero indicating a better goodness of ®t), the Chi-squared statistic (the higher the value the better), the McFadden R2 (again, the higher the better) and the number of correct predictions (again, the higher the better).

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Table 4 Variables included in regression model to explain WTP Description of variable

Variable name

Log of the bid amount o€ered to individuals Health outcomes Child from IVF (0 ˆ No, 1 ˆ Yes) Psychological outcomes One of the reasons we are trying (or tried) IVF is so that in later life I will know we have tried everything possible )1 ˆ strongly disagree to 7 ˆ strongly agree Even if we leave (or left) the IVF programme childless, I believe I will be (am) glad we tried it )1 ˆ strongly disagree to 7 ˆ strongly agree When we started the IVF programme I was very sure we would leave it with a child )1 ˆ strongly disagree to 7 ˆ strongly agree When our ®rst attempt at IVF failed I was surprised )1 ˆ strongly disagree to 7 ˆ strongly agree Score for total satisfaction with life scale Score for positive a€ects Score for negative a€ects Non-health outcomes Satisfaction with follow-up )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Process attributes Satisfaction with sta€ attitudes )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Satisfaction with chance of leaving with a baby )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Satisfaction with continuity of care )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Satisfaction with costs )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Satisfaction with time on the waiting list )0 ˆ completely dissatis®ed to 10 ˆ completely satis®ed a Overall I wish that the IVF programme did not exist )1 ˆ completely disagree to 7 ˆ strongly agree Autonomy I believe I have/had the choice myself to go through with IVF )1 ˆ strongly disagree to 7 ˆ strongly agreeAUTO1 I am/was happy with the extent of choice I have/had )1 ˆ strongly disagree to 7 ˆ strongly agree Personal Age (continuous) Sex (0 ˆ male, 1 ˆ female) Income (1 ˆ <£6,000, 2 ˆ £6,001±£10,000, 3 ˆ £10,001±£15,000, 4 ˆ £15,001±£20,000, 5 ˆ £20,001±£25,000, 6 ˆ £25,001±£30,000, 7 ˆ £30,001±£35,000, 8 ˆ >£35,000 Other factors Currently going through treatment (0 ˆ no, 1 ˆ yes) b Number of attempts had (continuous) Length of time trying to become pregnant (months)

LOGBID CHILD PSYCHO1 PSYCHO2 PSYCHO3 PSYCHO4 TSWLS PANAS(+ve) PANASN(-ve) FOLLOWUP ATTITUDES BABY CONTINUITY COSTS WAITING OVERALL AUTO1 AUTO2 AGE SEX INCOME CUR ATTEMPTS TIME

a Included in the regression equation following the use of ordered probit analysis which shows it to be a signi®cant predictor of overall satisfaction with the service. b Only included in logistic regression model for ex ante group.

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191

6. Results The results from the pilot study suggested that respondents understood the questionnaire and very few changes were made. Ignoring questionnaires which were undelivered (n ˆ 171), not appropriate or duplicates (n ˆ 54), a response rate of 57% was achieved in the main study (466/823). The average age of respondents was 36. Slightly more women than men returned the questionnaire (258 women compared to 208 men). 17% (78) of respondents were currently undergoing treatment and 80% (374) were not. The average number of attempts at IVF of respondents was 1.6 and the average length of time trying to become pregnant was seven and a half years. Of the 466 respondents, 12% had had a child from IVF. No information was available on non-respondents. Of the 466 respondents who returned the questionnaire, 458 (98%) completed the WTP question. Of the eight who refused, ®ve did not give a reason, one said they were not sure, one said they had decided not to proceed and therefore did not want to complete the questionnaire and one that his wife was pregnant from IVF so it was hard to take an objective view. Thus, there did not appear to be any `protest' answers i.e. respondents not answering the question because they have a moral objection to being asked WTP for health care. Responses to each bid amount are shown in the ®nal column of Appendix B. Of the 210 `couples' who responded to the questionnaire, 202 provided responses `consistent' with each other whilst eight couples provided responses `inconsistent' with each other. 6.1. Psychological outcomes Tables 1 and 2 show the results from the psychological scales used. The mean score on the SWLS scale was 22.59. Mean scores di€ered signi®cantly according to whether or not the respondent had had a child from the IVF programme: those with a child had a mean score of 25.68 compared to a mean score of 22.17 for those who had not conceived on the programme (p ˆ 0.001). This provides evidence that psychological outcomes are important in the provision of IVF services, and that leaving the service with a child, not surprisingly, leads to an improved psychological outcome. The mean score on the positive scale of PANAS was 32.24, with a standard deviation of 7.20. For the negative scale the mean was 18.72, with a standard deviation of 7.20. Thus, respondents report more positive a€ects than negative a€ects. Of total respondents, 56 had had a child from IVF and 403 had

192

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

not. The total scores on both the positive scale and negative scale were signi®cantly di€erent for these groups. As expected, those who had had a child scored signi®cantly higher on the positive scale (34.30 compared to 31.98, p ˆ 0.023) and signi®cantly lower on the negative scale (16.61 compared to 19.06, p ˆ 0.004). This again suggests that psychological outcomes are important in the provision of IVF services, and that leaving the service with a child also leads to an improved psychological outcome. Table 3 indicate the responses to the attitude statements. They suggest that there is some perceived utility from undertaking treatment, even if the individual leaves it childless. Of the total respondents, 89% agreed (responded with a 5, 6 or 7) to the statement `one of the reasons we are trying (or tried) IVF is so that in later life I will know that we have tried everything possible to have a child' (PSYCHO1). Further, 93% agreed (again, responded with a 5, 6 or 7) that even if they left the service childless, they would still be glad they had tried it (PSYCHO2). Similar ®ndings have been found elsewhere (Tymstra, 1989; Zoeten et al., 1987; Holmes and Tymstra, 1987). Of the respondents answering these statements, 88% had not conceived on the programme. There was no signi®cant di€erence in the distribution of responses to these statements according to whether or not the respondents had a child from the programme (PSYCHO1 1, Z ˆ )1.692; p ˆ 0.0906; PSYCHO2, Z ˆ )0.8794; p ˆ 0.3792). Thirty eight per cent of respondents agreed with the statement `when I started the IVF programme I was very sure that I would leave it with a child' (PSYCHO3) and 34% agreed that `when my ®rst attempt at IVF failed I was surprised' (PSYCHO4). There was no signi®cant di€erence according to whether respondents had a child from the IVF programme (PSYCHO3, Z ˆ )1.3083; p ˆ 0.1908, PSYCHO4, Z ˆ )0.2369; p ˆ 0.8128). These ®ndings suggest that individuals may experience some level of disappointment when going through the service and leaving it childless. 6.2. Regression analysis 307 respondents provided a full data set on WTP and all the independent variables that were included in the logit regression equations (as shown in Table 4). Of these, 229 provided an ex ante WTP valuation and 78 an ex post WTP valuation. The log model was chosen over the linear model due to the better goodness of ®t i.e. the log likelihood value was closer to zero, the chi-squared statistic was higher, the McFadden R2 was higher and there was a higher percentage of correct predictions. Table 5 shows the results

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

193

Table 5 Logistic regression results: Speci®c and general models for ex-ante group Attribute

Speci®c model

General model

Coecient

P

Coecient

P

11.92 )1.82

0.0000 0.0000

11.39 )1.91

0.0018 0.0000

)

)

0.95

0.1660

) ) 0.17 ) 0.09 )0.04 )

) ) 0.1022 ) 0.0022 0.1036 )

0.11 0.22 0.27 )0.20 0.08 )0.04 0.01

0.4873 0.4364 0.0470 0.1839 0.0119 0.1401 0.842

)0.21

0.0022

)0.22

0.0125

) ) ) 0.18 )

) ) ) 0.0108 )

0.06 0.01 )0.09 0.18 0.03

0.6351 0.9477 0.3862 0.0441 0.7353

0.3604 )

0.237 )

0.36 )0.09

0.0567 0.4907

)

)

)0.03

0.8768

Constant LOGBID Health outcomes CHILD Psychological outcomes PSYCHO1 PSYCHO2 PSYCHO3 PSYCHO4 TSWLS PANAS (+ve) PANAS ()ve) Non-health outcomes FOLLOWUP Process attributes ATTITUDES BABY CONTINUITY COSTS WAITING Autonomy AUTO1 AUTO2 Overall OVERALL Personal AGE SEX INCOME Other factors CUR ATTEMPTS PREG

) ) 0.20

) ) 0.0359

)0.01 0.24 0.24

0.7559 0.5519 0.0213

) ) )0.01

) ) 0.0052

0.28 )0.09 )0.01

0.5373 0.7559 0.0371

n Log-Likelihood McFadden R2 Chi-Squared Individual predictions

229 )103.5 0.34 108.110 (0.000) 76%

229 )99.2 0.38 116.6 (0.000) 77%

Median WTP Mean WTP a

£3902 £6829

£3947 £6552

a

Given the statistical properties of a log-normal distribution, if the log of the bid amount is entered as an independent variable in the logit regression equation, ea‡Rbx ˆ median WTP. The median has to be adjusted by the scaling factor p=b sin…p=b† to estimate mean WTP.

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M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

from the logistic regression model for the group that were placing a value on ARTs ex ante (i.e. providing a measure of cv), and Table 6 for the group who were placing a value on the service ex post (i.e. providing a measure of ev). Looking ®rst at the ex ante group, median WTP was estimated to be £3947 for the general model and £3902 for the speci®c model. Mean WTP was estimated to be £6552 for the general model and £6829 for the speci®c model. A number of the psychological outcomes were found to be signi®cant predictors of WTP. The more the respondent agreed with the statement `when we started the IVF programme I was very sure we would leave it with a child' (PSYCHO3), the more the individual was willing to pay for an attempt at IVF. This may re¯ect the fact that those individuals who perceive their chances of having a child from the IVF treatment to be high derive greater utility from the service. Individuals who scored more on the satisfaction with life scale (TSWLS) were willing to pay signi®cantly more. This is what we would expect, and provides further support for the importance of taking account of psychological outcomes when assessing the utility from IVF. Other variables included in the logistic regression model which were found to be signi®cant predictors of WTP were: satisfaction with level of follow-up support (the more dissatis®ed individuals are with the follow-up support, the more they are willing to pay ± this may be explained as follows ± if the individual feels that the follow-up is good, she may perceive that she is coming to terms with her infertility and therefore the need to go through IVF is reduced, thus reducing the monetary value of IVF), cost (the more satis®ed individuals are with the cost of treatment the more they are willing to pay); length of time trying to become pregnant (individuals who had been trying for a shorter length of time were willing to pay more); level of perceived choice in decision to go through ARTs (with individuals who agreed that they had the choice to go through with IVF being willing to pay more) and income (with individuals on a higher income being WTP more). Looking at the ex post group, the individual predictive power of both the speci®c and general model is noticeably higher than that for the ex ante group, suggesting a better goodness of ®t for this group. This may be explained in a number of ways. The dependent variable in the model is discrete i.e. `yes' or `no' depending on whether the respondent was willing to pay the amount o€ered to them. The greater the di€erence between the probability of saying `yes' or `no', the higher the predictive power of the model may potentially be. This is because we would expect a 50:50 chance that the predictive model is correct and the nearer the distribution of `yes' and `no' responses to 50:50 the more likely the model has predicted correctly through chance. This

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

195

Table 6 Logistic regression results: Speci®c and general models for ex post group Attribute

Constant LOGBID Health outcomes CHILD Psychological outcomes PSYCHO1 PSYCHO2 PSYCHO3 PSYCHO4 TSWLS PANAS (+ve) PANAS ()ve) Non-health outcomes FOLLOWUP Process attributes ATTITUDES BABY CONTINUITY COSTS WAITING Autonomy AUTO1 AUTO2 Overall OVERALL Personal AGE SEX INCOME Other factors ATTEMPTS PREG

Speci®c model

General model

Coecient

P

Coecient

P

25.64 )4.5015

0.0236 0.0020

34.96 )7.15

0.1336 0.0398

3.83

0.0647

5.70

0.1323

1.91 ) 2.44 )2.84 )0.38 ) )0.40

0.0412 ) 0.0056 0.0056 0.199 ) 0.0135

2.91 0.66 4.35 )4.95 )0.47 )0.16 )0.54

0.1237 0.705 0.1010 0.0801 0.1565 0.4431 0.1773

)

)

)0.031

0.4269

1.22 0.88 ) ) )1.30

0.1173 0.0323 ) ) 0.0098

1.85 1.65 0.30 )0.38 )2.20

0.4386 0.0957 0.5877 0.4520 0.0650

) )0.79

) 0.1000

)0.44 )1.07

0.6932 0.2425

)

)

)1.11

0.4862

) ) 1.31

) ) 0.0102

0.27 )1.64 2.00

0.4740 0.3728 0.0756

) 0.05

) 0.0203

0.38 0.05

0.6507 0.1305

n Log-Likelihood McFadden R2 Chi-Squared Individual predictions

78 )14.85 0.38 70.924 (0.000) 92%

78 )13.04 0.38 74.553 (0.000) 96%

Median WTP Mean WTP a

£2423 £2641

£1926 £1983

a Given the statistical properties of a log-normal distribution, if the log of the bid amount is entered as an independent variable in the logit regression equation, ea‡Rbx ˆ median WTP. The median has to be adjusted by the scaling factor p=b sin…p=b† to estimate mean WTP.

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M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

hypothesis is supported by the data on `yes' and `no' responses across the two groups. For example, in the ex ante group 45% of respondents gave a `no' response and 55% a `yes' response. By contrast, the corresponding ®gures for the ex post group were 65% saying `no' and 35% saying `yes'. A second explanation for the better goodness of ®t of the ex post model is that there may be variables that are more important to the ex post group than to the ex ante group. This is again supported by the data, with many of the variables in the model being of greater importance to the ex post group than the ex ante group (as indicated by the size of the coecients). Median WTP was estimated to be £1926 for the general model and £2423 for the speci®c model. Mean WTP was estimated to be £1,983 for the general model and £2641 for the speci®c model. A number of psychological outcomes were again found to be signi®cant predictors of WTP. The more the respondent agreed with the statement `even if we leave (left) the IVF programme childless, I believe I will be (am) glad we tried it', the more they were WTP for an attempt at ARTs. This suggests that there is some bene®t in going through the service, even if you leave it childless. The more the respondent agreed with the statement `when we started the IVF programme I was very sure we would leave it with a child' (PSYCHO3), the more the individual was willing to pay for an attempt at IVF. This may re¯ect the fact that those individuals who perceive their chances of having a child from the IVF treatment to be high derive greater utility from the service. However, the more the individual agrees with the statement `when our ®rst attempt at IVF failed I was surprised' (PSYCHO4) the less that person is willing to pay. This suggests that there may be some psychological disbene®t in expecting to leave the service with a child, and then leaving it childless. Thus, it cannot be assumed that leaving the service childless has no a€ect on psychological outcomes. The higher the individual scored on the PANAS()ve) scale, the less they were willing to pay. This suggests that individuals who have completed treatment and feel relatively negative about life value the service less than those who have completed treatment and feel relatively positive about life. This provides further support for considering psychological outcomes in the provision of ARTs. However, the higher respondents scored on the TSWLS, the less they were willing to pay. This contrasts with the ex ante group, where a higher score on the TSWLS led to an increased WTP. This ®nding for the ex post group may re¯ect the fact that given that they have ®nished treatment, those who scored higher on the TSWLS now feel less of a need to go through with treatment, thus re¯ected in a lower WTP. Thus, the improved psychological state, ex post, may be re¯ected in a lower valuation of the service.

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197

Other variables included in the logistic regression model which were found to be signi®cant predictors of WTP were: attitudes of sta€ (with respondents who were more satis®ed with sta€ attitudes being willing to pay more); satisfaction with chance of leaving the service with a baby (with those who were more satis®ed being willing to pay more); satisfaction with time on the waiting list, with those who were dissatis®ed being willing to pay more; whether or not the respondent had left the service with a child (with those who had left the service with a child being willing to pay more); length of time trying to become pregnant (with those who had been trying longer being willing to pay more); income (with those on a higher income being willing to pay more); and satisfaction with level of choice in decision to go through with IVF (with those disagreeing with the statement `I am/was happy with the extent of choice I have/had, being willing to pay more). 7. Discussion and conclusions This paper attempted to establish the importance of psychological outcomes when going through ARTs, using the economic instrument of WTP. The response rate of 57% was acceptable given that many of the individuals who received a questionnaire would have either left the mailing address or would no longer be involved in the ART programme. Arrow et al. (1993) recommended interviews when carrying out WTP studies. However, time and resource constraints meant that this was not possible in this study. However, the absence of protest bids, and the positively signi®cant coecient on income, providing support for the theoretical validity of the technique, suggest that mailed surveys are not to be dismissed in the design of WTP studies. Further empirical work is clearly needed on the reliability and validity of such survey designs. The main focus of this paper was to establish the presence of psychological outcome attributes in the infertile person`s utility function. Given this, the survey was carried out on ART users. (If the question was concerned with the public provision of ARTs, and WTP was to form the basis of a cost-bene®t analysis, the sample should be a random sample of the population at large, and not solely those involved in the ART programme (Arrow et al., 1993; Gafni, 1991). Values elicited from users will include both `user' and `non-user' values i.e. the `caring externality' (Culyer, 1976) and `option value' (Weisbrod, 1964).

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Whilst the results from this work suggest that psychological factors are important in the provision of ARTs, given the limited experience with WTP in a health care context, these results should be interpreted with caution. A statement was included in the WTP questionnaire telling respondents that there was no way that they would have to pay the bid amount they were o€ered and that the aim of the question was only to ®nd out how much they value ARTs. This statement was included in the wording of the WTP question for a number of reasons. Using the WTP technique in the area of health care in the British National Health Service (NHS) is politically sensitive and has to be adapted accordingly. It is not like asking respondent's WTP for environmental goods. Experience of using the WTP technique in the British NHS has shown that providers of health care are concerned that including WTP questionnaires will lead to suggestions that they are attempting to privatise the health care system. Such providers have therefore insisted on such a statement being included if WTP is to be used as an instrument to value health care interventions. Inclusion of this statement was also intended to reduce `protest bids' i.e. respondents not answering the question because they have a moral objection to being asked WTP for health care. It is recognised that such a statement may induce hypothetical bias by inviting respondents to overstate their WTP and that work is therefore needed on the validity of the WTP technique using this statement. However, in the only empirical study testing the `overpledging hypothesis' Bohm (1972) found no evidence of respondents overstating their WTP when they are told that they would not actually have to pay anything, no matter what they said they would be WTP. Bohm looked at respondents WTP to see a preview of a Swedish television show. He was concerned with numerous aspects of strategic bias, including free-riding and overbidding. Respondents were allocated to one of ®ve possible payment situations: actual payment of the WTP o€ered by each individual; payment amount proportional to WTP; lottery chooses payment method; ®xed payment of 5 Kroner and no payment required. In the ®rst two scenarios free riding was hypothesised, in the third no strategic behaviour was expected and in the latter two overbidding was expected. However, Bohm found that respondents were not sensitive to the strategic incentives included in the experiment, and that the WTP amounts revealed in the ®ve scenarios were not statistically signi®cantly at any accepted signi®cant level. The results indicate that the psychological feelings of `regret' and `disappointment' may be major motivators for individuals seeking ARTs. Regret theory and disappointment theory have been developed by economists to explain consistent violations of the axioms of expected utility theory (Bell, 1982;

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

199

Loomes and Sugden, 1982; Bell, 1985; Loomes and Sugden, 1986). However, to date they have been applied mainly to individual decision making involving uncertain monetary rewards. Regret theory is based on the premise that one of the reasons individuals carry out certain acts, or take certain risks, is to prevent regretting not having taken a given course of action in later life. The statistical signi®cance of the response to the statement `one of the reasons we are trying (or tried) IVF is that in later life I will know we have tried everything possible' in explaining WTP suggests that attempting to prevent regret may be an important motivational factor in the decision to go through ARTs. Disappointment is de®ned as a psychological reaction to the outcome of an event not living up to its expectations. For individuals undergoing ARTs there is uncertainty about the outcome of treatment. The negative signi®cance of the statement `when our ®rst attempt at IVF failed I was surprised' suggest that the more individuals agreed with this statement, the less they valued ARTs. This suggests that the psychological feeling of disappointment may be an important factor when looking at total utility from undertaking IVF. Given that individuals consistently overstate their chances of leaving the service with a child (Ryan, 1995), this negative psychological outcome is likely to be important. The importance of the psychological feeling of regret, and knowing you have done everything possible to have a child, is supported by the ex post valuation of IVF. Whilst WTP was substantially higher for the ex ante group, the positive valuation provided by the ex post group suggests that there is some bene®t from going through the service, even if you leave it childless. Of the 78 individuals who gave an ex post valuation, 65 had left the service childless. Whilst those who had a child from IVF gave a signi®cantly higher valuation than those who had left it childless, the childless still provided a positive valuation for the service. Thus, it is wrong to ignore the childless when looking at user values in the economic evaluation of ARTs. In conclusion, this paper has attempted to go beyond the cost per live birth approach to assessing the bene®ts from ARTs, and to take account of psychological outcomes in the infertile person's utility function. The economic instrument of WTP was used to attempt to measure the importance of these outcomes in the provision of the service. Important messages emerged from this study for economists concerned with the economic evaluation of ARTs. When looking at user values, the evaluation of such treatments should be concerned with more than whether the users leave the service with a child. More speci®cally, economists should note both the presence of psychological outcomes in the infertile person's utility function,

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M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

and the potential applicability and sensitivity of the WTP technique to take account of such outcomes. Acknowledgements The author is grateful to all respondents who completed questionnaires, to Cam Donaldson and John Cairns for comments on earlier drafts of this paper and to two anonymous referees for comments on a previous version of this paper. The author is an MRC Senior Research Fellow at the HERU. HERU is funded by the Chief Scientist Oce of the Scottish Oce Department Health (SODH). The views expressed in the paper are those of the author and not SODH. Appendix A. Closed-ended willingness to pay question In this Section I am concerned with how you value IVF treatment. One way to do this is to ®nd what the maximum amount of money is that you would be willing to pay for each IVF attempt you have. You will not have to pay the amount you state. This is just a way of ®nding out how strongly you feel about IVF. 1. Would you be willing to pay £2000 for your current attempt at IVF? If you are not currently undergoing IVF would you be willing to pay £2000 for your next attempt at IVF? If you do not intend to have another attempt at IVF, would you be willing to pay £2000 for your last attempt at IVF, knowing what you know now? Remember that any money you spend on IVF will not be available for you to spend on other things. So, would you be willing to pay £2000 2 for your current, next or last attempt at IVF? (Please tick appropriate box.) Yes

No

2

Bid amount varied from £110.00 to £20,000.

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201

2. Could you please state the reasons for your answer in question 1. Appendix B. Bid vector for closed-ended study and responses

Amount (£) 110.00 300.00 470.00 640.00 790.00 940.00 1090.00 1230.00 1360.00 1490.00 1620.00 1740.00 1860.00 1980.00 2100.00 2220.00 2340.00 2450.00 2570.00 2690.00 2800.00 2920.00 3040.00 3160.00 3280.00 3400.00 3530.00 3660.00 3800.00 3930.00 4080.00

Number sent out 18 23 22 21 21 20 20 20 19 19 19 19 18 18 18 18 18 18 18 18 18 18 18 18 19 19 19 19 20 20 20

Number returned

P(YES)

12 7 11 9 11 6 5 10 8 8 11 10 5 12 3 7 6 8 8 11 12 6 7 9 10 4 9 9 6 10 11

1 1 1 1 0.83 1 0.80 0.80 0.87 0.75 0.91 0.90 0.80 0.69 0.67 0.71 0.50 0.50 0.70 0.75 0.50 0.17 0.71 0.60 0.60 0.50 0.67 0.44 0.50 0.40 0.36

202

4230.00 4380.00 4550.00 4730.00 4910.00 5120.00 5340.00 5590.00 5870.00 6190.00 6580.00 7070.00 7750.00 8880.00 10 000.00 15 000.00 20 000.00 Total

M. Ryan / Journal of Economic Psychology 19 (1998) 179±204

21 21 22 23 23 24 26 27 29 32 35 41 53 24 18 18 18

7 7 12 4 11 9 14 11 16 15 10 16 22 14 7 7 9

1048

458

0.43 0.38 0.50 0 0.18 0.11 0.28 0.09 0.35 0.44 0.20 0.18 0.26 0.21 0.14 0.28 0.11

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