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Biomedical subjects

Mandy Ryan

Publications and source records attributed to Mandy Ryan.

At least 19 recordsLinked to original sources
PubMed2006

Exploring preference anomalies in double bounded contingent valuation.

Double bounded dichotomous choice (DBDC) contingent valuation offers increased efficiency of willingness to pay (WTP) estimates compared with the single bounded format. However, evidence suggests DBDC generates anomalous respondent behaviour. This paper provides the first investigation and explanation of these anomalies in health. Results suggest the incentives for truthful preference revelation are altered in the presence of a follow up question. This result is found using both regression techniques and analysis of raw responses. Although findings suggest 'very certain' respondents exhibit less anomalous behaviour inconsistencies remain across bounds. The results of this study question the use of iterative valuation formats.

Air Ambulances↗
PubMed2006

Using discrete choice experiments to estimate a preference-based measure of outcome--an application to social care for older people.

This paper reports the results of a study that used discrete choice experiment (DCE) methodology to estimate quality weights for a of social care outcome measure. To reflect different states of need, a five-dimensional profile measure was developed. Experimental design techniques were used to derive a sample of states for which preferences were elicited. The DCE approach was employed to elicit values and regression techniques used to estimate a model that could predict index scores for all 243 possible outcomes. The utility model, estimated on the basis of 297 responses, had good test-retest reliability and converged with preferences elicited from a rating exercise.

Aged↗
PubMed2006

Women's preferences for cervical cancer screening: a study using a discrete choice experiment.

OBJECTIVES: Recent policy recommendations for cervical screening include liquid-based cytology. This new approach could improve laboratory throughput, reducing the waiting time for test results. New guidelines also standardize the interval for screening, with women aged 25-50 offered screening every 3 years and women aged 50-64 every 5 years. Quantitative evidence on the preferences of women for alternative screening programs is limited; this study, therefore, elicits such preferences. METHODS: A postal questionnaire using a discrete choice experiment was mailed to 2,000 women in the Tayside Health Board region of Scotland. RESULTS: A response rate of 44 percent from those women who had previously had a smear was achieved. Women had a significant positive preference for reductions in recall rates and waiting time for results. Women preferred more frequent screening, particularly those aged 50+. Expected reductions in the chance of recall from the conventional Pap smear to the new liquid-based cytology were associated with a willingness to pay of pound 41. Women aged 50+ would be willing to pay pound 42 to increase the frequency of screening from every 5 to every 3 years. Service characteristics did not influence screening participation. CONCLUSIONS: Guidance to move to liquid-based cytology will meet women's preferences for fewer repeat cervical smears and should reduce waiting time for results. However, proposals to increase screening intervals for those aged 50+ are inconsistent with the preferences for this age group. From a policy perspective, our study results suggest that the changes in attributes of the service such as unsatisfactory smear rates and frequency of screening, will improve service efficiency without affecting participation rates.

Adult↗
PubMed2006

Preferences for self-care or professional advice for minor illness: a discrete choice experiment.

AIM: To determine the relative importance of factors that influence decision making in the management of minor illness, and how people trade between these factors. DESIGN OF STUDY: Discrete choice experiment. SETTING: Scottish electoral roll. METHOD: Six hundred and fifty-two responders of a previous national survey were invited to complete a discrete choice experiment questionnaire. This was used to measure relative preferences for managing symptoms of minor illness often associated with analgesic use. Three attributes were identified as important to participants: type of management, availability, and cost of managing symptoms. Trade-offs between these attributes were examined. RESULTS: A 57% response rate was achieved (51% valid response rate). People preferred to manage symptoms by self-care and were willing to pay almost pounds 23 to do so. Community pharmacy was the preferred source of advice. Responders preferred less waiting time and paying less money when managing symptoms, and were willing to trade between factors. A less preferred type of management became more attractive when waiting times and cost were reduced. CONCLUSION: Findings suggest that self-care is the preferred method of managing symptoms of minor illness. When developing services to support self-care, policy makers should invest in services that reduce waiting times and incur least cost to users.

Adult↗
PubMed2005

'Irrational' stated preferences: a quantitative and qualitative investigation.

Individuals' rationality has been a key issue long debated in Economics. While normative theories establish the way 'rational' consumers should behave, many empirical studies have documented numerous systematic violations of normative principles. This has led some to question the validity of classic economic models as an adequate approximation of individuals' real decision-making. This paper aims to shed more light on this debate. A stated preference choice experiment was set up to test rational choice properties. Attention was given to the extent to which satisfaction of such tests is related to both the complexity of the design, and subject characteristics. Quantitative and qualitative methods are applied. The majority of respondents passed the rationality tests. Satisfaction of the tests was sensitive to normatively irrelevant factors such as the complexity of the task and demographic characteristics. A significant proportion of those individuals who 'failed' seem to have reformulated the experiment in some way in their mental process. Implications for the design and analyses of future DCEs are discussed.

Adult↗
PubMed2005

'Threats' to and hopes for estimating benefits.

In a recent paper in this journal, Andrew Lloyd reviewed some potential threats to the estimation of health care benefits in monetary terms. Particular emphasis was placed on the extent to which the use of non-compensatory heuristics may distort the results. Although it is useful to be reminded of these problems, Lloyd's paper does not do justice to the attention such issues have already received, and continue to receive, within Health Economics. The aim of this paper is twofold. Firstly, it seeks to provide a more balanced and comprehensive view of the evidence by considering some of the methodological work that health economists have conducted in many of the areas pointed out by Lloyd. Secondly, and more importantly, it suggests ways to combine the economic and psychological views of human decision-making, providing a much more positive perspective to all those researchers out there who recognize the necessity of using stated preference methods to inform health policy.

Choice Behavior↗
PubMed2005

Rapid prenatal diagnostic testing for Down syndrome only or longer wait for full karyotype: the views of pregnant women.

OBJECTIVES: Prenatal diagnosis by karyotype analysis determines the copy number and structure of each chromosome and is considered to be the 'gold standard' in detection of chromosome abnormality. This method is, however, time consuming and women may have to wait up to 21 days for the results. With improving molecular genetic techniques, the most commonly occurring chromosome abnormalities can be diagnosed within 2 days from amniotic fluid. This study investigates the value pregnant women place on these alternative prenatal diagnostic tests. METHODS: A structured self-completion discrete choice experiment questionnaire was designed. The subjects were 40 pregnant women, of unknown risk, attending for their 11-week booking scan and 10 elevated-risk women attending for amniocentesis at the Aberdeen Maternity Hospital, Scotland. RESULTS: Women value 'comprehensive' information of a full karyotype analysis at pounds 791, and 'simple' information of a rapid diagnostic test at pounds 690. Willingness to pay for a day's reduction in waiting time for results is pounds 18. Women prefer a prenatal service providing simple over comprehensive information as long as they receive results 6 days sooner than the comprehensive results would be provided. CONCLUSIONS: While women prefer comprehensive information, the bulk of the value is placed on knowing whether the fetus has Down syndrome. Given the longer wait times for comprehensive information, simple information is preferred as long as results are received 6 days sooner than would be the case for comprehensive information. These results have implications for the resources dedicated to providing a rapid prenatal diagnostic service.

Adolescent↗
PubMed2005

Using discrete choice experiments to go beyond clinical outcomes when evaluating clinical practice.

BACKGROUND: This study builds on the results of a randomized controlled trial concerned with examining the effect of reducing waiting times on the health status of patients referred for non-urgent rheumatology opinion. No difference in clinical outcomes was found between a 'fast-track' and 'ordinary' appointment system. This suggests that rationing by waiting times is not detrimental to health. However, such an approach ignores the value patients attach to reducing waiting time. OBJECTIVES: To estimate the monetary value of reducing waiting time, as well as changes in duration of appointment and the introduction of a pain management service, in the provision of rheumatology services. METHODS: Discrete choice experiment (DCE). SETTING: The main outpatient clinic of the rheumatology service for the Lothian and Borders region. SUBJECTS: 262 patients who had received a specialist rheumatology opinion--73 had received fast-track treatment, 65 standard care and 124 were non-trial patients. RESULTS: A response rate of 71% was achieved. Patients valued a 9-week reduction in waiting time at 131 pounds sterling. However, the introduction of a pain management service was valued at 209 pounds sterling. Thus, the latter is of more value to respondents. Evidence was also found of the internal consistency and theoretical validity of the DCE approach. CONCLUSIONS: The reduction of waiting times is a central plank of NHS policy. Whilst a reduction in waiting time is of value, a pain management service is of more benefit than a 9-week reduction in waiting time. DCE were shown to be a potentially useful technique for valuing different aspects of health care interventions.

Clinical Medicine↗
PubMed2004

A comparison of stated preference methods for estimating monetary values.

This paper presents a comparison of willingness to pay (WTP) estimates generated from a dichotomous choice (DC) contingent valuation experiment and a choice experiment (CE). The study was conducted with subjects undergoing assisted reproductive techniques in the Grampian area of Scotland. Subjects first completed a DC WTP questionnaire. They were sent a CE questionnaire two months later. Welfare estimates for the DC WTP study and CE were not significantly different. Important research questions are raised concerning the validity of the various approaches to estimating WTP.

Financing, Personal↗
PubMed2004

Modelling non-demanders in choice experiments.

Discrete choice experiments have the advantage that they can study preferences in health care where revealed preference data is not readily available. However, as a substitute for actual observed market led data, the experimental set-up for hypothetical situations must mimic the circumstances under which actual choices are made. One situation that a consumer/patient might face is an opt-out option. They might not choose to accept any of the positive actions available and as such will be a non-demander of the health care on offer. This paper explores issues raised in the modelling of such data within an experiment looking at women's preferences for cervical screening services.

Choice Behavior↗
PubMed2004

Deriving welfare measures in discrete choice experiments: a comment to Lancsar and Savage (1).

Lancsar and Savage argue that current methods of deriving welfare estimates, using discrete choice experiments, are inconsistent with random utility and welfare theory. In this paper I show that this not the case. The general formula proposed by Small and Rosen for estimating welfare, which Lancsar and Savage claim should be used, reduces to the method used by health economists for state of the world models. The important question then becomes when are state of the world models, as opposed to multiple alternative models, appropriate?

Asthma↗
PubMed2004

Valuing health care using willingness to pay: a comparison of the payment card and dichotomous choice methods.

This paper compares willingness to pay (WTP) estimates generated from the dichotomous choice (DC) and payment card (PC) approaches. In a split-sample WTP experiment concerned with allocating scarce health care resources across three health care interventions, the DC approach is shown consistently to generate larger welfare estimates than the PC. Observed difference between PC and DC experiments cannot be explained by the inclusion of non-demanders or methods of statistical analysis but may be partly explained by "yea-saying". No evidence of range bias or mid-point bias was found with PC responses. Data were also collected on respondents' ordinal rankings of the three interventions and person-trade-offs (PTOs). Neither of these approaches converged with WTP. Future work must address the decision heuristics individuals employ when responding to valuation experiments.

Air Ambulances↗
PubMed2004

Valuing the benefits of weight loss programs: an application of the discrete choice experiment.

OBJECTIVE: Obesity is a leading health threat. Determination of optimal therapies for long-term weight loss remains a challenge. Evidence suggests that successful weight loss depends on the compliance of weight loss program participants with their weight loss efforts. Despite this, little is known regarding the attributes influencing such compliance. The purpose of this study was to assess, using a discrete choice experiment (DCE), the relative importance of weight loss program attributes to its participants and to express these preferences in terms of their willingness to pay for them. RESEARCH METHODS: A DCE survey explored the following weight loss program attributes in a sample of 165 overweight adults enrolled in community weight loss programs: cost, travel time required to attend, extent of physician involvement (e.g., none, monthly, every 2 weeks), components (e.g., diet, exercise, behavior change) emphasized, and focus (e.g., group, individual). The rate at which participants were willing to trade among attributes and the willingness to pay for different configurations of combined attributes were estimated using regression modeling. RESULTS: All attributes investigated appeared to be statistically significant. The most important unit change was "program components emphasized" (e.g., moving from diet only to diet and exercise). DISCUSSION: The majority of participants were willing to pay for weight loss programs that reflected their preferences. The DCE tool was useful in quantifying and understanding individual preferences in obesity management and provided information that could help to maximize the efficiency of existing weight loss programs or the design of new programs.

Adult↗
PubMed2004

Are women's expectations and preferences for intrapartum care affected by the model of care on offer?

OBJECTIVE: To investigate the effect of service provision on consumer preferences, in particular, whether women who have access to systems of care which offer particular attributes (such as continuity of carer) value these attributes more highly than women for whom the attributes are not a realistic option. DESIGN: Simple rating scales and a discrete choice experiment were used to assess the importance to women of different aspects of intrapartum care. SAMPLE AND SETTING: The sample consisted of 301 women at low obstetric risk, identified from three geographical areas, each with a different system of maternity care provision. METHODS: Midwives gave an anonymous, self-complete questionnaire to the women at the booking visit. Categorical data from the rating scales were analysed using the chi(2) test. Analysis of the discrete choice experiment was conducted using random effect probit regression. Main outcome measures Women's preference for different attributes of intrapartum care. RESULTS: From the rating scales, it appeared that women in the area with least continuity rated this aspect of care significantly lower than women in other areas (P= 0.007). Although the discrete choice experiment appeared to confirm this, the difference was not statistically significant. CONCLUSIONS: The findings from this study suggest that the systems of care on offer do influence women's preferences for aspects of intrapartum care. Women in areas where continuity of carer was a realistic option appeared to value this aspect of care more highly. The tendency for preferences to be influenced not only by previous experience of a service but also by knowledge of its availability has important implications for the inclusion of consumers' values in deciding whether to introduce innovations in care. It has been suggested that greater consumer involvement may be a useful means of challenging the accepted view of what is important in health services and of facilitating change. However, the findings from this study suggest that consumer views may have the opposite effect. If consumers do prefer what they know, then a policy of tailoring health services to local preferences will simply reinforce current provision of services, reinforcing existing inequalities in the provision of care.

Adult↗
PubMed2003

Revisiting the axiom of completeness in health care.

Experiments concerned with modelling individual preferences are based on the assumption of completeness i.e. it is assumed that individuals have well-defined preferences for any choice they are presented with. However, this may not be the case for goods such as health care, where individuals are not used to making choices. If this assumption is violated, the large body of experimental economic literature eliciting patient preferences in health care may be challenged. This paper reports the results of a discrete choice experiment carried out to examine the assumption of complete preferences within health care. The tests carried out are based on the comparison of preferences for three different goods for which different levels of formed preferences are expected: a supermarket; dentist consultation and bowel cancer screening. The results do not provide sufficient evidence to support this hypothesis. However, further research is required before these results are generalised.

Attitude to Health↗
PubMed2003

Estimating the monetary value of health care: lessons from environmental economics.

In the recent past, considerable effort in health economics has been made on applying stated preference methods such as contingent valuation and choice experiments. Despite this increased use, there is still considerable scepticism concerning the value of these approaches. The application of contingent valuation in environmental economics has a long history and has been widely accepted. Whilst choice experiments were introduced to the environmental and health economics literature at a similar time, the wider acceptance of monetary measures of benefit in environmental economics has meant that they have also been more widely applied. The purpose of this paper is to identify some of the key issues and debates that have taken place in the environmental economics literature, summarise the state of the art with respect to these issues, and consider how health economists have addressed these issues. Important areas for future research in health economics are identified.

Attitude to Health↗