AP stat pt2

Population

The entire group of individuals or objects that is the focus of an investigation.

Sample

A smaller subset of individuals selected from the target group to provide data for a study.

Simple Random Sample (SRS)

A selection design where every possible group of a specified size has an equal likelihood of being chosen.

Stratified Sampling

A method where the target group is divided into distinct subgroups sharing characteristics, and individuals are randomly selected from each subgroup.

Cluster Sampling

A method where the target group is divided into preexisting intact groups, whole groups are randomly selected, and every individual inside those groups is studied.

Systematic Sampling

A method where individuals are chosen at fixed regular intervals from an ordered list after a random starting point (such as selecting every $k^{\text{th}}$ individual, like every $5^{\text{th}}$ or $10^{\text{th}}$).

Convenience Sampling

A non-probability method that selects individuals who are easiest to reach or most readily available.

Voluntary Response

A selection scenario where participants decide for themselves whether to take part in an open invitation or public survey.

Nonresponse

A scenario where selected individuals cannot be reached or refuse to participate in the study.

Response Bias

A pattern of inaccurate reporting caused by external influences, such as leading question wording or interviewer behavior.

Undercoverage

A flaw where specific segments of the target group are systematically omitted or given a reduced chance of selection by the sampling frame.

Bias

A systematic flaw in a design or estimation process that consistently overestimates or underestimates the true parameter value.