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Convergent interviewing and respondent-driven sampling

Bill Harris writes,

I stumbled across this project today and thought it might be related to a comment I posted last summer here.

I’m curious if Bob Dick’s convergent interviewing perhaps predates RDS; I’m pretty sure I first learned convergent interviewing from Bob around 1992. I have a book by him, Rigor Without Numbers, that talks about convergent interviewing, as well. While my third edition is copyright 1999, it says that the first version was delivered at the XVIIIth Annual Meeting of Australian Social Psychologists, Greenmount, Queensland, 12-14 May 1989.

For more online on convergent interviewing, see here.

Matt responds:

I was not familiar with convergent interviewing and it does seem that it precedes RDS; as far as I know the first paper about RDS was published by Doug Heckathorn in 1997. But, it also seems that the methods are very different. RDS is designed to make population proportion estimates (e.g. What percentage of drug injectors in New York City have HIV?) while it seems that convergent interviewing is designed for qualitative research. Also, in convergent interviewing it seems that the researcher chooses who to interview next (and so can do this in a purposive way), but in RDS the choice of who gets recruited is made by the participants themselves, not the researcher, and in fact RDS estimation only works if people recruit randomly from their friends (i.e. no purposive choice). There may be insights that practitioners of both methods can learn from each other, but those connections aren’t clear to me right now. On the other hand, sometimes these connections pop up in mysterious ways, so this idea might be helpful in the future.

Bill adds:

What I saw as qualitatively similar between MCMC and convergent interviewing is the notion that you draw a sample in ways that seeks to maximize the information you gather from your sample, avoiding getting stuck in parts of the population that have very little to contribute to items of interest, as you might with a purely random sample.

I seem to recall it being said somewhere that one can select the next people to interview in CI by asking the current pair of respondents (i.e., on an iterative basis) who is the person most unlike them who is also in some sense mainstream. As I haven’t gotten time to do much with your paper yet, I can’t speak to RDS except via your claim that it relates to MCMC.

As for the intent, I think what you say is correct, although Bob Dick may wish to offer his views: CI is focused on qualitative research, and so you’re more likely to surface a broad spectrum of answers but have no estimate of relative frequency of those answers in the population.

One Comment

  1. David says:

    Reading Bill's comment reminded me of the idea behind unscented transformations.