AP Statistics Unit 3 Sampling Vocabulary

Census

Selects all items/subjects in a population.

Population

The entire group of individuals (not necessarily people) that we want information about.

Sample

A subset of the population.

Sampling frame

List of individuals who actually had the chance to be included in the sample.

Sample design

Method we use to select a sample.

Response Bias

Sample is not representative of the population. Occurs when certain responses are systematically favored over others.

Statistics

A numerical summary of a sample.

Parameters

A numerical summary of a population.

Voluntary Response Sample

When a sample is comprised entirely of people who choose to participate, the sample will typically not be representative of the population.

Convenience Sample

Select individuals who are conveniently available.

Simple Random Sample

A sample in which every group of a given size has an equal chance of being chosen.

Systematic Random Sampling

A method in which sample members from a population are selected according to a random starting point and a fixed, periodic interval.

Stratified Random Sample

Involves the division of a population into separate groups based on shared attributes or characteristics (homogeneous grouping). Within each group a simple random sample is selected, and the selected units are combined to form the sample.

Cluster Sample

Divide population into heterogeneous groups. Randomly select one or more groups and include ALL individuals from those groups in the sample.

Multistage Sample

Combining several sampling methods.

Undercoverage

When part of the population has a reduced chance of being included in the sample, the sample will typically not be representative of the population.

Nonresponse Bias

Individuals chosen for the sample for whom data cannot be obtained (or who refuse to respond) may differ from those for whom data can be obtained.

Question wording bias

Problems in the data gathering instrument or process result in bias. Examples include questions that are confusing or leading and self-reported responses.

Sampling without replacement

An item from a population can be selected only once.

Random number generator

Numbering individuals and using a random number generator to select which ones to include in the sample, ignoring repeats.

Valid sampling

All valid sampling must be selected randomly.