Stratified sampling is a method of sampling that involves dividing the population into subgroups or strata based on some characteristic or criteria (such as age, gender, income level, geographic location, etc.) and then selecting a random sample from each subgroup in proportion to its size. This method ensures that the sample represents the diversity of the population and increases the precision of the estimates by reducing the variability within each stratum. It is commonly used in market research, opinion polls, and survey studies where the population is heterogeneous and stratification can help to capture the important subgroups for analysis.
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