Karen Blumenschein

Eliciting Willingness to Pay Without Bias: Evidence from a Field Experiment

Concern exists that hypothetical willingness to pay questions overestimate real willingness to pay. In a field experiment, we compare two methods of removing hypothetical bias, a cheap talk approach and a certainty approach, with real purchases. We find evidence of hypothetical bias for unadulterated contingent valuation. Contingent valuation with certainty statements removes the hypothetical bias, but the cheap talk approach has no significant impact. Our findings suggest that willingness to pay can be accurately estimated by adding a simple follow-up question about the certainty of responses and that cheap talk is not a generally effective approach.

Hypothetical versus real willingness to pay in the health care sector: results from a field experiment

Abstract We conducted a field experiment comparing hypothetical and real purchase decisions for a pharmacist provided asthma management program among 172 subjects with asthma. Subjects received either a dichotomous choice contingent valuation question or were given the opportunity to actually enroll in the program. Three different prices were used: US

Calibrating Hypothetical Willingness to Pay Responses

15, 40, and 80. In the hypothetical group, 38% of subjects said that they would purchase the good at the stated price, but only 12% of subjects in the real group purchased the good ( p =0.000). We cannot, however, reject the null hypothesis that “definitely sure” hypothetical yes responses, as identified in a follow-up question, correspond to real yes responses. We conclude that the dichotomous choice contingent valuation method overestimates willingness to pay, but that it may be possible to correct for this overestimation by sorting out “definitely sure” yes responses.

Relationship between quality of life instruments, health state utilities, and willingness to pay in patients with asthma

Experimental data comparing hypothetical and real dichotomous choice responses for two different goods were used to estimate a statistical bias function to calibrate the hypothetical yes responses. The probability that a hypothetical yes response would be a real yes response was estimated as a function of the individuals self-assessed certainty of the hypothetical yes response (assessed on a 0–10 scale) and a variable representing the price level. Without calibration the hypothetical yes responses significantly exceeded the proportion of real yes responses, but after calibration the null hypothesis of no difference between hypothetical and real responses could not be rejected in any of the experiments.

Eliciting Willingness to Pay Without Bias Using Follow-Up Certainty Statements: Comparisons Between Probably/Definitely and a 10-Point Certainty Scale

BACKGROUND In asthma, a substantial impact of disease is on quality of life rather than survival. To date, the quality of life effects of asthma have not been quantitated. OBJECTIVE The purpose of this study was to quantitate the quality of life effects of asthma via measurement of the health utility of asthmatic patients, and the willingness to pay for an asthma cure. A second goal was to analyze how these measures are related to the different dimensions of quality of life as measured by general and disease specific quality of life instruments. METHODS Health utilities were measured on a scale between 0 and 1 using the rating scale, time trade off, and standard gamble methods. Willingness to pay was elicited using both the dichotomous choice and the bidding game approach. Quality of life was assessed using both a generic instrument (the SF-36) and a disease-specific instrument (the Asthma TyPE). RESULTS Sixty-nine patients with asthma were surveyed. The mean health utility was 0.68 with the rating scale method, 0.89 with the time trade off, and 0.91 with the standard gamble. On average, patients were willing to pay between

Assessment of the relationship between measures of disease severity, quality of life, and willingness to pay in asthma.

200 to

Outcomes from DiabetesCARE: A pharmacist-provided diabetes management service

350 dollars more per month for an asthma cure. Nearly all correlations between dimensions of quality of life, health state utilities, and willingness to pay were in the expected direction. CONCLUSION The two quality of life instruments performed about equally well in terms of being correlated with and being able to explain the responses to the health state utility questions and the willingness to pay questions. Correlations between the dimensions of the Asthma TyPE and the SF-36 were also fairly high. Further work should focus on validating and refining the different methods of quantitating quality of life for asthma patients.

Economic evaluation in healthcare. A brief history and future directions.

Correction for hypothetical bias using follow up certainty questions often takes one of two forms: (1) two options, “definitely sure” and “probably sure”, or (2) a 10-point scale with 10 very certain. While both have been successful in eliminating hypothetical bias from estimates of WTP by calibrating based on the certainty of yes responses, little is known about the relationship between the two. The purpose of this paper is to compare the two using data from three field experiments in a private good, dichotomous choice format. We compare four types of yes responses that differ in the criterion used to determine if there is sufficient certainty for a hypothetical yes response to be considered a true yes response. We make several comparisons, but focus on determining which values on the 10-point scale give the same estimates of WTP as “definitely sure” hypothetical yeses and real yeses (actual purchases). Values that produce equivalence are near 10 on the certainty scale.

Hypothetical versus real payments in Vickrey auctions

AbstractObjective: The primary objective was to evaluate the relationship between willingness-to-pay (WTP), quality-of-life (QOL), and disease-severity measures in patients with asthma. The hypothesis studied was that patients with asthma with more severe disease are willing to pay more for a hypothetical cure of asthma than those with less severe disease. Design setting/Patients and participants: One hundred patients with asthma were recruited from community pharmacies in Kentucky for 30-minute face-to-face interviews. Interventions: Spirometry assessed objective disease severity in terms of pulmonary function, while a multiple choice question measured subjective disease severity. The Medical Outcomes Study 36-item Short Form (SF-36) health survey and Asthma Technology of Patient Experience (Asthma TyPE) measured quality of life. WTP was obtained via a dichotomous choice contingent valuation question. Results: In this exploratory evaluation, WTP was significantly related to both objective disease severity (p = 0.02) and subjectively assessed disease severity (p = 0.01). For objective disease severity the mean monthly WTP was

Atypical antipsychotic initiation and the risk of type II diabetes in children and adolescents

US90 for mild asthma,