AP Stats Ch. 4 Terms

Simple Random Sample (SRS)

A sample chosen so that every group of n individuals in the population has an equal chance of being selected as the sample.

Margin of Error

The difference between the point estimate and the true parameter value will be less than the margin of error in C% of all samples, where C is the confidence level.

Population

The entire group of individuals we want information about.

Parameter

A number that describes some characteristic of the population.

Census

Collects data from every individual in the population.

Sample

A subset of individuals in the population from which we actually collect data.

Sample Survey

A study that collects data from a sample chosen to represent a specific population.

Convenience Sample

A sample selected by taking individuals from the population who are easy to reach.

Bias

Occurs when the design of a statistical study is very likely to underestimate or overestimate the value being studied.

Voluntary Response Sample

A sample consisting of people who choose to participate by responding to a general invitation.

Random Sampling

Uses a chance process to determine which members of a population are included in the sample.

Strata

Groups of individuals in a population who share characteristics thought to be associated with the variables being measured.

Stratified Random Sampling

Selects an SRS from each stratum and combines them into one overall sample.

Cluster

A group of individuals in the population who are located near each other.

Cluster Sampling

Randomly selects clusters and includes every member of the selected clusters in the sample.

Undercoverage

Occurs when some members of the population are less likely to be selected or cannot be selected in a sample.

Nonresponse

Occurs when an individual chosen for a sample cannot be contacted or refuses to participate.

Response Bias

Occurs when there is a systematic pattern of inaccurate answers to a survey question.

Statistic

A number that describes some characteristic of a sample.

Survey

An investigation that collects data from a sample to estimate the characteristics of a population using statistical methods.

Random Digit Table

A chance device used to select experimental units or conduct simulations.

Study Versus Experiment

In an experiment, researchers impose treatments or control variables. In an observational study, researchers observe individuals without imposing treatments.

Systematic Sampling

Selects sample members using a random starting point and a fixed periodic interval.

Inference for Sampling

The process of drawing conclusions about a population based on sample data.

Question Wording

The way survey questions are phrased, which can influence how respondents answer.

Probability Sample

A sample in which every element in the population has a known statistical likelihood of being selected.