Most stated preference studies estimate discount rates using a split-sample approach. Each sample faces a different payment frequency (for instance, 1, 5, 10) together with a randomly assigned bid vector; both the frequency of payments and the bid are fixed for a specific individual. This paper evaluates whether allowing respondents to choose their preferred payment frequency affects the estimated discount rate. We use data from a contingent valuation survey of a network of marine reserves and estimate discount rates using both an exogenous and endogenous approach. The former calculates the mean of the willingness to pay (WTP) for each sample and then finds the discount rate that makes the present value of each payment frequency equivalent. The latter estimates the WTP and the discount rate jointly. Results show that allowing people to choose the payment schedule significantly reduces the implicit discount rate. We observed the highest reductions in discount rates when we used all the information available from the valuation questions to bound the WTP distribution. Our analysis suggests that the exogenous approach would not be recommended for testing the adequacy of people’s responses to the frequency of payments.

大多数陈述的偏好研究使用拆分样本方法估算折现率。每个样本都面临着不同的付款频率（例如1、5、10）以及随机分配的出价矢量；付款频率和出价都是针对特定个人的。本文评估允许答卷者选择他们喜欢的支付频率是否会影响估计的贴现率。我们使用来自海洋保护区网络的或有估值评估的数据，并使用外生和内生方法来估算折现率。前者计算每个样本的支付意愿（WTP）的平均值，然后找到使每个支付频率的现值相等的折现率。后者共同估算WTP和折现率。结果表明，允许人们选择付款时间表会显着降低隐式折扣率。当我们使用估值问题中的所有可用信息来约束WTP分配时，我们观察到贴现率的最大降幅。我们的分析表明，不建议使用外生方法来测试人们对支付频率的反应是否足够。