This document defines key statistical concepts: - Statistics is the subject that deals with collecting, analyzing, and interpreting data. It can also refer to the data itself or summary measures calculated from samples. - A population includes all individuals or objects with common characteristics being studied. A sample is a subset of a population selected to represent it. - A parameter is a characteristic of the entire population, such as the population mean, which remains fixed. A statistic is a characteristic calculated from a sample, such as the sample mean, which can vary between samples.