This document discusses sampling, which is a statistical method used to obtain representative data from a large group or population. A sample is a subset of elements selected from the overall population that represents the characteristics of the entire group. For a sample to be effective, it needs to be representative, adequate in size, independent, homogenous, lack bias, and be accurately and completely collected. The sample frame contains information used to identify and select the sample units, which are single elements chosen for research and statistics about the whole population.