Expe method

Experiment

A controlled investigation where one or more independent variables are manipulated to test their effect on a dependent variable.

Independent Variable

Any variable that can be manipulated in an experiment.

Dependent Variable

The criterion by which the results of the experiment are judged.

Experimental Group

Group of subjects exposed to the experimental treatment.

Control Group

Subjects that are exposed to the control condition.

Randomization

Assignment of subjects and treatment to groups based on chance.

Extraneous Variables

Variables other than manipulated variables that affect the results of the experiment.

Demand Characteristics

Aspects of the experiment that provide unintentional hints to subjects about the experimenter's hypothesis.

Experimenter Bias

Effects on subjects' behavior caused by an experimenter's presence, actions, or comments.

Blinding

Technique used to control subjects' knowledge of whether they have been given the experimental treatment.

Internal Validity

Indicates whether the independent variable was the sole cause of the change in the dependent variable.

External Validity

Indicates the extent to which the results of the experiment are applicable to the real world.

Maturation Effect

Effect on experimental results caused by experimental subjects maturing or changing over time.

One-Group Pretest-Posttest Design

Diagrammed as O1 X O2, this design includes pretesting and posttesting within the same group.

Quasi-Experimental Designs

Research designs where complete control over potential confounding variables cannot be achieved.

Factorial Design

Used to examine the effects of manipulating at least 2 independent variables.

Main Effect

The impact that each independent variable has on the dependent variable.

Interaction Effect

The impact on the dependent variable caused by interaction between independent variables.