Estimating Income Effects Using a Sample of Lottery Players

9812057 Imbens之前的一个项目(国家科学基金会拨款编号SBR9423018)收集了参加马萨诸塞州彩票的人的数据，包括那些赢得一次性小奖的人和那些在20年内获得大奖的人。这个项目使用这些数据来比较那些在彩票中玩并中了大笔钱的人，即“赢家”，与那些玩彩票但没有中大笔钱的“失败者”；比较的点包括他们的劳动力供应、消费和储蓄行为，以及他们孩子的教育成就和支出。收集彩票数据的关键原因是利用彩票中的随机性来重建一个以收入注入为治疗条件的随机实验。由于三个原因，即调查中的回复率为50%，中奖概率取决于所购彩票的数量(这个变量只是不完全观察到的)，以及中奖者与失败者来自不同的人群，不同组之间存在预处理差异。调查人员寻求各种方法来处理调整，以使随后的比较更可信。初步结果表明，调整前的差异导致了对收入对劳动力供应因果效应的可信估计。

9812057 Imbens A previous project (NSF grant number SBR9423018) collected data on people who played the Massachusetts lottery, including those who won small onetime prizes and people who won large prizes paid out over twenty years. This project uses these data to compare people who played and won large amounts of money in the lottery, "winners", with people who played the lottery but did not win large amounts of money "losers"; the points for comparison include their labor supply, consumption and savings behavior, and the educational achievement of, and expenditures for, their children. The critical reason for collecting lottery data was to exploit the randomization in the lottery to reconstruct a randomized experiment with an infusion of income as the treatment condition. For three reasons, namely the response rate in the survey was 50%, the probability of winning the lottery depends on the number of tickets bought (a variable which is only imperfectly observed), and the winners were drawn from a different population than the losers, there are pretreatment differences between the various groups. The investigators pursue a variety of methods to deal with adjustments to make the subsequent comparisons more credible. Preliminary results suggest that adjusting for pretreatment differences leads to credible estimates of the causal effect of income on labor supply.