We focus here on potentially ambiguous and problematic
types of sampling situations, which occur often in health
care sampling contexts. These situations may occur and
be addressed at a study’s design phase, and, because the
design should determine the analysis, our discussion has
implications for the analysis, too. Our objective is to
provide illustrations of these situations and offer guid-
ance for choosing more efficient and appropriate solu-
tions to sampling design and analysis challenges.