Use the Questionnaire or Open-Ended Interview Questions?

We have found that the quality of participants and the "show rate" is higher if you recruit in an apparently more casual and personable way, using a screener as a checklist during a more conversational interview. Here you can ask open-ended questions to get the respondents to volunteer information about themselves that will reveal whether they qualify. There are several advantages to this approach. First, you build rapport with the candidate, he rapport results in a stronger feeling of responsibility and commitment in the participants. They are more likely to show up for the session and be on time. Second, it is less likely that the candidate will give an answer just because he or she thinks it is the correct one to get into the study. Third, you can as follow-up questions that may expand or clarify something important study. Finally, you can make better on-the-flv adjustments to your selection criteria. Tins doesn't mean that you're biasing the sample, but instead it helps you incorporate things you learn as you interview respondents and make intelligent tradeoffs if some requirement or other becomes difficult to meet For example, Dana worked on a study of a web site for registered voters 

She wanted people from both rural and urban places (a classifier), but the study took place at harvest time. Many of the people in rural places would only be available after sundown (and a very, v ery hard day) or if it rained If Dana had used only a scripted questionnaire, she might not have found out Poople weren't available. But in a casual conversation, she found out whv and what the options were for getting these types of participants.