Friday, February 13, 2015

Adaptive Designs and Incentives

I've been working on a paper about an incentive experiment that we did. It raised some interesting issues. And made me recall one of my favorite papers. Trussell and Lavrakas looked at incentives to a follow-up survey. They found that if someone had refused or been difficult to contact in the initial, screening survey, then a higher incentive was needed than for someone who had not refused or been difficult to contact. The incentives they recommend also differed by some demographic characteristics as well.

I liked this example since the adaptation was linked, in part, to the paradata. These are the kinds of adaptations I have the most interest in. They require learning on the part of the survey organization that happens during data collection. I have the feeling that these kinds of adaptations can be particularly powerful since in models predicting response, it is often the case that paradata overwhelm the predictive power of demographic characteristics.

There are all sorts of ethical and procedural issues with offering differential incentives that make it difficult to carry out in practice, but I still think this is a neat example.

Friday, February 6, 2015

Understanding "Randomly Selected"

I had the opportunity this morning to meet with a medical researcher who runs many clinical trials. He spoke about the problems of explaining randomization when enrolling persons in a trial. It's hard to be sure they understand the concept of randomization. To be sure, it's even more difficult to be sure they understand the consequences of either enrolling or not enrolling in a trial. But the problem of explaining randomization caught my attention.

This reminds me of the situation that interviewers find themselves in quite frequently. In implementing random selection of a person from within a household, they often find that the person selected is someone other than the informant who aided with the selection. In these cases, the informant may be disappointed that they weren't selected and ask if they can do the interview instead. It's often difficult to explain why we want to speak to the other person, who is not there or maybe not even willing to do the interview.

It certainly takes a skillful respondent to explain the concept of random sampling in that situation. It might be that research into explaining this concept to participants in a clinical trial would help us arm interviewers to respond to these kinds of questions.