Experimental Design: Control, Validity, and Threats in Cause-and-Effect Research

What is the purpose of manipulating independent variables in an experiment?

To observe the effect they have on dependent variables.

What is a controlled situation in an experiment?

A setup where each independent variable is systematically altered for different participants.

Why are experiments considered the best study design for assessing cause-and-effect relationships?

They allow for manipulation of variables and control of other potential causes.

What are the two essential requirements for testing cause-and-effect in an experiment?

Control of other variables and manipulation of the independent variable.

What is the Matching Groups Approach in experimental design?

A method where membership in each group is strategically designed to make groups look relatively the same.

What is the Randomization Approach in experimental design?

A method where participants are randomly assigned to groups, giving each an equal chance of appearing in any group.

What is a Quasi-Experiment?

An experimental design that includes manipulation but lacks randomization.

What does internal validity refer to in experimental design?

The rigor with which the study was conducted and the extent to which cause-and-effect inferences can be made.

What does external validity refer to in experimental design?

The extent to which findings are generalizable to other settings or populations.

What is the trade-off between internal and external validity in experiments?

Lab experiments have more internal validity but less external validity, while field experiments have more external validity but less internal validity.

What is the History effect in experimental validity threats?

When outside events or factors impact the outcomes being studied.

What is the Maturation effect in experimental validity threats?

When the outcome is influenced by the passing of time.

What is the Testing effect in experimental validity threats?

When the outcome is influenced by repeated testing.

What is the Selection effect in experimental validity threats?

When there is bias or poor representation among participants.

What is the Mortality/Attrition effect in experimental validity threats?

When some participants leave partway through the experiment.

What is the Statistical Regression effect in experimental validity threats?

When an initial unusual result returns to normalcy.

What is the Instrumentation effect in experimental validity threats?

When the outcome is affected by the test or measure being used.

What is the main purpose of conducting experiments?

To develop and test theories.