Being surveyed can change later behavior and related parameter estimates.

Does completing a household survey change the later behavior of those surveyed? In three field studies of health and two of microlending, we randomly assigned subjects to be surveyed about health and/or household finances and then measured subsequent use of a related product with data that does not rely on subjects' self-reports. In the three health experiments, we find that being surveyed increases use of water treatment products and take-up of medical insurance. Frequent surveys on reported diarrhea also led to biased estimates of the impact of improved source water quality. In two microlending studies, we do not find an effect of being surveyed on borrowing behavior. The results suggest that limited attention could play an important but context-dependent role in consumer choice, with the implication that researchers should reconsider whether, how, and how much to survey their subjects.

How Much do Existing Borrowers Value Microfinance? Evidence from an Experiment on Bundling Microcredit and Insurance.

Randomized controlled trials have found only modest effects of microfinance, but these studies focus on new clients. Existing estimates may thus understate ongoing gains for more experienced borrowers and the longer-run potential of microfinance. We estimate impacts of microfinance on experienced borrowers, using an episode when a microfinance institution modestly increased existing clients' fees in randomly selected villages (in exchange for a mandatory health insurance policy that turned out to be useless). This increase in fees led to a 22 percentage point decline in loan renewal in treatment villages (95% confidence interval: 16 to 27), compared to control villages where the policy was not introduced. Using this randomly generated variation in microfinance participation among experienced borrowers, we find impacts of microfinance that are strikingly similar to previous estimates for new clients: neither business outcomes nor household consumption were affected, on average. Also, consistent with prior studies, we find significant impacts on business outcomes among clients who had started their businesses before microfinance entered the village (0.06 standard deviation decline in an index of business outcomes from the loss of microfinance, 95% confidence interval: -0.002 to -0.12). However, despite these measured losses, these clients were just as willing to give up microfinance.