hair dryer for most of the interview.   The enumerator was doing a good job of shooing other people away (friends, family members, hair salon staff who weren't working) but clearly, waiting for this woman to finish what was a non-trivial hair treatment was going to be an issue -- so we went ahead. How do you know if someone has a document?   This evaluation covers business registration, so we really care whether folks have a certificate.   Alas, it seems like a lot of people in the pretest (some of whom we knew were registered) keep their certificate at home (they aren't required to post them by any law).   So one might suspect that the respondents are lying because they either want to please you or they think you work for the government (things you have to train the enumerators to avoid). But, one guy we were talking with gave a good explanation for this -- during some fairly recent urban unrest, his shop had been damaged and looted. So home was safer.     So how do we make sure this guy really has a certificate? Our approach is to allow for multiple codes in the response: yes has a certificate and shows it and yes has a certificate but doesn't show.    David and his coauthors Suresh de Mel and Chris Woodruff took a different approach in Sri Lanka. In that case the treatment was conditional on producing some documents, and for other documents they offered an incentive to respondents in terms