While some interview research is quantitative, like survey research, most interview projects are qualitative in nature. In qualitative research, there is less concern for finding a research sample that is perfectly representative of the population you want to study. This does not mean that you do not want to get a variety of perspectives in the interview process – rather, it means that you will not be making claims that your research is generalizable to the population at large, so your sampling procedure will not be as exhaustive as it is when conducting a survey.
Let's return to the Metamorphosis Project example. In that case, we spoke with five pastors who worked in our study area. There were more than five Catholic Churches in our area, so we knew that these five pastor did not necessarily represent the perspectives of every pastor. But since interviews take a good amount of time to conduct and analyze, we knew we could only speak to a few – we felt that the five pastors with whom we spoke gave us a good enough insight in order to draw some conclusions about their experiences and the likely experiences of others working in that area.
The big question that we often get from people who want to conduct interviews is, how many should I conduct? There is no single answer to this question. Usually one or two is not enough if you are trying to understand a complex phenomenon, so we would suggest, at the very least, to try to talk to four or five people. Some projects conduct dozens or even hundreds of interviews. While this can be very useful, it is not always necessary to talk to this many people. When you are conducting interviews, what you are really looking for is a saturation point – that is, a point in time when few, if any, new topics, issues, or ideas are being brought up by your interview respondents that you have not heard before. So your best bet, when you have the time to do so, is to interview until you have reached saturation.
As for recruitment of participants, this can take many forms. Do you have a list of people who would be good to speak to? Give them a call or send them a letter. Is there a particular place where you can find potential participants – like an office, or a public space? If so, go there and see if they would be willing to participate. Recruitment can be difficult at times, so don't get discouraged. If you can show the participants that you value their time and opinions, they will likely be happy to take part.
Get Participatory! There are a number of reasons to include those individuals who you want to study in the research process itself. This can often improve the ethics and relevance of your research. One way to get participatory in the sampling process is by training a few community members to do some of the outreach themselves - this might improve your reach as an organization and will give an important level of ownership in the research process to those people who get involved.