Russel-Research-Method-in-Anthropology

8
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Nonprobability Sampling and
Choosing Informants
If your objective is to estimate a parameter or a proportion from a sample to
a larger population, and if your research calls for the collection of data
about attributes of individuals (whether those individuals are people or organizations
or episodes of a sitcom), then the rule is simple: Collect data from a
sufficiently large, randomly selected, unbiased sample. If you know that you
ought to use an unbiased sample, and you have the means to get an unbiased
sample, and you still choose to use a nonprobability sample, then expect to
take a lot of flak.
There are, however, three quite different circumstances under which a nonprobability
sample is exactly what is called for:
1. Nonprobability samples are always appropriate for labor-intensive, in-depth studies
of a few cases. Most studies of narratives are based on fewer than 50 cases,
so every case has to count. This means choosing cases on purpose, not randomly.
In-depth research on sensitive topics requires nonprobability sampling. It can
take months of participant observation fieldwork before you can collect narratives
about topics like sexual and reproductive history or bad experiences with
mental illness or use of illegal drugs.
Come to think of it, just about everything is a sensitive topic when you dig
deeply enough. Sexual history is an obviously sensitive topic, but so is the
management of household finances when you get into how people really allocate
their resources. People love to talk about their lives, but when you get
into the details of a life history, you quickly touch a lot a nerves. Really in-
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