AP Statistics Vocab Quiz 4: Methods of Sampling (4.2)

Lurking Variable

A variable that is not among the explanatory or response variables in a study but that may influence the response variable.

Replication

An experimental design principle that requires the use of enough experimental units in each group so that any differences in the effects of the treatments can be distinguished from chance differences between the groups.

Block

A group of experimental units that are known before the experiment to be similar in some way that is expected to affect the response to the treatments.

Comparison

An important experimental design principle that requires two or more treatments to avoid confounding of the effect of a treatment with other influences, such as lurking variables.

Observational Study

This is the process where data is gathered on individuals as they are. It measures variables of interest but does not attempt to influence the responses.

Random Assignment

An experimental design principle that requires the use of some chance process to assign experimental units to treatments. This helps create roughly equivalent groups of experimental units by balancing the effects of lurking variables that aren’t controlled on the treatment groups.

Placebo Effect

Describes the fact that some subjects respond favorably to any treatment, even an inactive one.

Confounding

When two variables are associated in such a way that their effects on a response variable cannot be distinguished from each other.

Experiment

This is the the process that deliberately imposes some treatment on individuals to measure their responses.

Single-Blind

An experiment in which either the subjects or those who interact with them and measure the response variable, but not both, know which treatment a subject received.

Double-Blind

An experiment in which neither the subjects nor those who interact with them and measure the response variable know which treatment a subject received.

Randomized Block Design

An experimental design where the treatments are assigned to all the experimental units completely by chance.

Control

An important experimental design principle that requires two or more treatments to avoid confounding of the effect of a treatment with other influences, such as lurking variables.

Subject

When the experimental units are human beings.

Matched Pair Design

A form of randomized block design for comparing exactly two treatments by matching pairs of similar experimental units.