This document discusses research sampling methods. It defines key terms like population, sample, and sampling frame. It explains that sampling involves selecting a subset of a population to make inferences about the entire population. There are two main types of sampling: probability and non-probability. Probability sampling gives all population elements an equal chance of selection and includes simple random sampling, systematic sampling, stratified sampling, and cluster sampling. Non-probability sampling does not give equal selection chances and includes convenience sampling and purposive sampling like judgment and quota sampling. The document outlines features of a good sample and steps in sampling design to accurately represent a population with minimal error.