Experimental Design
Our main experiment was conducted in the Busia and Samia Districts of Western Kenya from February to May, 2010. In our sample, parents reported that 23% of their children had a worm infection in the previous year. To obtain as representative a sample of households as possible, a door-to-door census was conducted with 1,547 households in two villages located roughly 11 kilometers apart (Ikonzo and
Bhukulungu). The census collected basic information, including whether the household had a male or female head, the number of children in the household, and the GPS location of the household. With this data, we created 51 geographic clusters based on the GPS coordinates, and randomly selected 1,069 households for project participation, stratified by geographic cluster. We were able to interview 999 of these (93.4%).
We implemented four main experimental treatments, all cross-cut against each other. All treatments were conducted after administering a baseline survey (discussed below), and obtaining informed consent. First, we estimate an experimental demand curve by implementing a methodology based on Kremer and Miguel (2007), Cohen and Dupas (2010), Dupas (2009), and Ashraf, Berry, and Shapiro (2010). In particular, we visited households and provided them with a coupon offering a random discount on the shoes. The market price at the time was about 85 Ksh ($1.13), and we provided households with coupons for 5, 15, 25, 35, 55, or 65 Ksh. Coupons were valid for a period of about 2 months. Then, to measure the impact of information on health investment, we randomly selected half of the households to receive an information script on the symptoms of worms, transmission pathways, and on several strategies to prevent infection, including wearing shoes, using pit latrines, and hygiene. We used a script, rather than a more involved educational seminar, because results from our earlier studies in Guatemala, India, and Uganda suggested that a script had similar impacts to a seminar. To measure the role of liquidity, we provided households with randomly varying cash payments. As part of our baseline survey, we elicited risk and time preferences for all households using standard laboratory techniques. For the risk preference questions, households were given a series of choices in which they could decide how much to invest (out of 40 Ksh or 100 Ksh) in an asset which paid out three times the amount invested with probability 0.5 and nothing with probability 0.5. For the time preference questions, households were given the option of accepting 40 Ksh immediately or a larger amount in the future. Lastly, to measure whether there are differences within the household in the willingness to invest in health technology in households with both a female and male head, we randomly selected either the husband or the wife for the intervention.
There are three main pieces of data that we use to evaluate the program. First, at baseline, we administered a background survey to all sampled households. In addition to standard demographic questions, we collected information on child health, worm exposure, and shoe ownership. We also collected information on household knowledge of worms, transmission pathways, and prevention strategies at the end of the survey. After the survey, we paid households their random cash payout and gave them a coupon which could be redeemed at a local shop for the price indicated. The shops were located in market centers that households would typically visit regularly for shopping (approximately 1.5 kilometers away from the average household). The coupon was pre-printed with the household’s ID number on it, so that any redeemed coupon could be matched to our household data. We hired an enumerator to supervise the redemption and maintain a log containing the name of the person redeeming the coupon, the number of coupons redeemed at one time, and the sizes of the shoes purchased. Lastly, we conducted a follow-up survey with 379 randomly selected households once the redemption period had ended (about 3 months after the first coupons had been given out). The follow-up survey included questions on shoe usage, as well as the same module used to measure worm knowledge in the baseline.