SOCI 2030 Lecture 6: Chapter 6- Sampling Part 4
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You divide them into a homogenous population with subgroups: defined: the grouping of the units composing a population into homogeneous groups (or strata) before sampling. In stratified sampling, a researcher first divides the population into sub-population (strata) on the basis of supplementary information (e. g. , age, gender). After dividing the population into strata, the researcher draws a random sample from each subpopulation. He or she can sample randomly within strata using simple random or systematic sampling. In stratified sampling, the research controls the relative size of each stratum, rather than letting the random processes control it. This guarantees representativeness or fixes the proportion of different strata within a sample. Of course, the necessary supplemental information about strata is not always available. In general, stratified sampling produces samples that are more representative of the population than simple random sampling if the stratum information is accurate. A simple example illustrates why this is so.
