This document discusses sampling design for research. It explains that sampling design refers to the method used to collect data from a subset of a population. A proper sampling design starts with a sample that is representative of the population. There are two main types of sampling: census, which investigates all individuals in a population, and sampling, which uses a small number from the larger population due to constraints. The document outlines key concepts in sampling design including the target population, study population, sampling frame, probability and non-probability sampling methods, and factors to consider for an appropriate sample size and design.