Closed-ended Format Research Articles

Valuing the benefits of mobile mammographic screening units using the contingent valuation method

The benefits of improving access to mammographic screening are estimated using a contingent valuation experiment conducted on 458 women in 19 rural Australian towns. The contingent valuation survey provides women with information on mammographic screening and uses a closed-ended format to elicit their willingness to pay for a visit of a mobile mammographic screening unit. Single and double-bounded versions of the discrete response contingent valuation method are employed in the estimation of willingness to pay. The double-bounded contingent valuation approach is shown to be biased due to respondents having a greater disposition to respond ‘no’ when the bid amount in the follow-up question is higher than the bid amount offered in the initial question. Several approaches to dealing with this bias are examined.

Comparison of Open and Closed Questionnaire Formats in Obtaining Demographic Information From Canadian General Internists

The objective of this study was to compare the impact of closed- versus open-ended question formats on the completeness and accuracy of demographic data collected in a mailed survey questionnaire. We surveyed general internists in five Canadian provinces to determine their career satisfaction. We randomized respondents to receive versions of the questionnaire in which 16 demographic questions were presented in a closed-ended or open-ended format. Two questions required respondents to make a relatively simple computation (ensuring that three or four categories of response added to 100%). The response rate was 1007/1192 physicians (80.0%). The proportion of respondents with no missing data for all 16 questions was 44.7% for open-ended and 67.0% for closed-ended formats (P < 0.001). The odds of having missing items remained higher for open-ended response options after adjusting for a number of respondent characteristics (2.67, 95% confidence interval 2.01 to 3.55). For the two questions requiring computations focused on professional activity and income, there were more missing data (P = 0.02, 0.02, respectively) but fewer inaccurate responses (P = 0.009, 0.20, respectively) for the open-ended compared to the closed-ended format. Investigators can achieve higher response rates for demographic items using closed format response options, but at the risk of increasing inaccuracy in response to questions requiring computation.

On the gap between payment card and closed-ended CVM-answers

The paper presents contingent valuation (CV) estimates of benefits provided by a proposed ‘Kalkalpen’ National Park in Austria. Although descriptive results of welfare measures are presented, the focus of the paper is on methodological questions concerning the analysis of CV answers. Evidence is given regarding the difference between payment card (PC) answers and closed-ended question formats. Based on different estimation models for CV questions substantial differences are found between closed-ended and payment card welfare measures. On average PC-willingness to pay (WTP) measures are below the closed-ended figures. Since the evaluation models are based on different premises in the calculation of WTP figures a more precise disclosure of the underlying evaluation methods is required if different question formats are compared to one another. Identical assumptions on the probability distributions have to be assumed whenever open- and closed-ended CV welfare measures are compared. Taking theoretical arguments into account the application of the closedended double-bounded Spike model that provides an average welfare measure is recommended.

Contingent valuation experiments for strategic behavior

The existence and extent of strategic disclosures in field contingent valuation surveys have been debated but few empirical studies are available. This paper summarizes the results of an experiment to identify strategic behavior using alternative disclosure mechanisms with closed-ended and open-ended formats. In addition, the experiment examined the effect of mechanism design on respondent's ability and willingness to disclose their personal valuation. Statistical results using censored discrete regression analysis and nonparameteric means tests provide some evidence of systematic differences due to strategic behavior. But the comparisons are inconclusive due to the significant influence of sample selection on valuation results using closed-ended formats and the inherent limitations of comparative means test procedures. Evidence from this analysis cannot refute the hypothesis that respondents try, to the best of their ability, to provide truthful information. But the procedures used to interpret this information can have a significant effect on aggregate valuation results.