Controlled sampling for comparing two populations - An example
Krotki, K., & Porcellini, L. (1990). Controlled sampling for comparing two populations - An example. Proceedings of the Survey Research Methods Section (ASA), 683-687.
When the objective of a study is to compare with respect to one
variable two populations that are inherently different along related
dimensions, a standard probability sample is not always appropriate
since there is no control over extraneous variables that may be
related to the key indicators of interest. This paper discusses a
sample designed to study the effect of ethnicity on drinking behavior by
comparing Irish and Puerto Ricans in New York City. A random sample of
both populations would have almost certainly produced an Irish sample
with a higher average socioeconomic level than the Puerto Rican sample.
Furthermore, since the total sample size was only 1,000, limiting the
analysis to the comparable subpopulations would have resulted in
unacceptably small effective sample sizes. Controlled sampling was used
to favor selection of areas which according to census data contained
members of each ethnic group of similar socioeconomic background I .
The paper concentrates on the preparation of the sample frame which
is the innovative aspect of this design.