True Experimental Design

Vocabulary terms and definitions related to true experimental design, covering variables, group types, and sampling methods.

Independent Variable

The variable that the experimenter controls and manipulates to create $2$ or more groups in a study, serving as the cause in a cause-and-effect relationship.

Dependent Variable

The outcome variable or the one being measured in an experiment, serving as the effect in a cause-and-effect relationship.

Control Group

The natural or baseline group in an experiment used for comparison against the group receiving a change.

Experimental Group

The group in an experiment that receives some kind of change to their natural environment.

Placebo Effect

When a participant changes their behavior simply because they expect a change to occur.

Random Assignment

A process where each person in a study has an equal chance of being placed in either the control group or the experimental group to ensure groups are identical except for the independent variable.

Population

The entire, relatively large group of people that a researcher is interested in studying.

Sample

The smaller group of people actually participating in the study, drawn from the larger population.

Convenience Sample

A sample chosen by using people who are readily available and willing to participate, such as friends or family.

Clustered Sample

A specific type of convenience sample that is based on a particular geographic area.

Random Sample

A sample in which every person in the larger population has an equal chance of being included, intended to be representative of the population.

Stratified Random Sample

A sampling method where the population is divided based on important variables identified in advance, followed by randomly choosing an equal number of people from each group.