- Количество слайдов: 12
Willingness to Pay (WTP) Dr Cho-Min-Naing MBBS, DMA, MMed. Sc (Ygn), MSc (Bkk), Ph. D ( ld) Medical doctor, Yangon, Myanmar
Performance objectives: At the end of this session, the participants will be able to understand how to formulate a survey of WTP. Learning objectives: To equip with knowledge of WTP. To formulate a WTP study.
Introduction What is WTP? WTP is defined as the maximum amount of money that may be contributed by an individual to equalize a utility change. WTP is one approach to the valuation of health benefits. The technique is based on the principle 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.
Why do we do a WTP study? Direct measurement of WTP for particular goods or services can be assessed by asking people directly how much they would be willing to pay for specific health care services or products. This approach allows individuals to take account of all factors (e. g. disposable income, taste, education level, severity of illness etc. ) which are important to them in the provision of the service. For direct measurement of an individual’s WTP for non-market goods, the contingent valuation (CV) method is attractive.
The CV method: What & How? Two approaches to the CV method: (i) open-ended valuation questions using a bidding game approach, and (ii) binary valuation questions. Each of these two valuation methods, binary valuation and the bidding game, has its own limitations.
Essence of the bidding game In open-ended valuation questions, respondents are asked to state their maximum WTP for the service. A so-called “bidding game”, which resembles an auction, is used. 1. Potential consumers are presented with a detailed description of the hypothetical scenario, and a description of the product or service being evaluated. 2. Potential consumers are asked questions concerning their estimation of the maximum amount they would be WTP to obtain or prevent a hypothetical specified change in health.
Performing a bidding game To collect information on WTP for the new diagnostic test for malaria (that is, the ICT Malaria Pf/Pv test kit or the card test in this example), we did our assessment with the CV method, using a bidding game approach. The bidding game technique was introduced to assess patients’ valuation of the card test for malaria. Step 1: Description of the card test was demonstrated to patients. The aim was to show it works easily, rapidly, and conveniently for the patient. (That is for on-the-spot-diagnosis).
Analysis & discussion of WTP: In general, regression analysis is used to assess WTP studies. WTP has been positively associated with education, income and beliefs, and the ideological acceptance of health care (Golan and Shechter, 1993). For further information, see Cho-Min-Naing et al. (2000), Bhati & Fox-Rushby (2002) etc. as shown in the suggested readings.
Caveat inverter: With respect to interpreting the findings of WTP studies, it must be stressed that great care has to be taken because there is always a suspicion that what subjects say they would pay and what they would actually pay may be different. Since the choices are hypothetical rather than real, it is important to interpret the results of studies using the CV method with caution.
Suggested reading: 1. Bhati M, Fox-Rushby, Willingness to pay for treated mosquito nets in Surat, India: The design and descriptive analysis of a household survey. Health Policy & Planning 2002; 17: 402 -11 2. Cho-Min-Naing, Lertmaharit S, Kamol- Ratanakul, Saul A. Ex post & ex ante WTP for the ICT malaria Pf/Pv test kit in Myanmar. Southeast Asian J Tropical Med Public Health 2000; 31: 104 -11 3. Drummond MF, O’Brien BJ, Stoddart GL, Torrence GW. Methods for the economic evaluation of health care programmes. 2 nd ed. , Oxford University Press, New York, 1997; 222 4. Golan EH, Shechter M. Contingent valuation of supplemental health care in Israel. Med Decis Making 1993; 13: 302 -10.
Suggested reading (cont): 5. Johannesson M. A note on the relationship between ex ante and expected willingness to pay for health care. Soc Sci Med 1996; 42: 305 -11 6. Klose T. The contingent valuation method in health care. Health Policy 1999; 47: 97 -123 7. Mansfield E. Preference regarding risk. In: Microeconomics. Theory and Applications, 9 th ed. W. W. Norton and Company, Inc. New York. 1997; 145 8. Mathiyazhagan K. Willingness to pay for rural health insurance through community participation in India. Int J Hlth Plan Mgmt 1998; 13: 47 -67 9. O’Brien, Viramontes. Willingness to pay: A valid and reliable measure of health state preference? Med Decis Making 1994; 14: 289 -97
Suggested reading (cont): 10. O’Brien B, Gafni A. When do the dollars make sense? Towards A conceptual framework for contingent valuation studies in health care. Med Decis Making 1996; 16: 288 -99 11. Pindyck RS, Rubinfeld DL. Shifts in supply and demand. In: Microeconomics. Prentice Hall, New Jersy. 4 th ed. 1998; 22 12. Sorum PC. Measuring patient preferences by willingness to pay to avoid: The case of acute otitis media. Med Decis Making 1999; 1: 27 -37 13. Stalhammar Nils-Olov. An empirical note on willingness to pay and starting point bias. Med Decis Making 1996; 16: 242 -47