Do Survey Spot-Check and Threat Improve Data Quality? Evidence from a Field Experiment

In this study, we examine the effect of interview observation on data quality of a large-scale individual survey in Vietnam. External spot-check teams were sent to randomly selected enumeration areas to attend and observe survey training courses and field interviews of interviewers. We find that interviewers have a lower number of item non-responses in collected data when being observed by the spot-check teams. The effect of a spot-check of field interviews appears to be higher than the effect of a spot-check of training courses. However, we do not find a significant effect of a spot-check threat: informing interviewers of a possible spot-check without actually visiting does not reduce item non-responses.