Complex Experimental Designs

What is the simplest experimental design regarding levels of an independent variable?

It has only two levels of the independent variable (IV).

Why might researchers use three or more levels of an independent variable?

To provide more information about the relationship, especially if a curvilinear relationship is predicted.

What is a factorial design?

An experimental design with more than one independent variable (or factor).

What does a 2x2 factorial design entail?

It has two independent variables, each with two levels, resulting in four experimental conditions.

What are the two kinds of information yielded by factorial designs?

Main effects and interactions.

What is a main effect in the context of factorial designs?

The direct effect of an independent variable on a dependent variable.

What is an interaction in factorial designs?

The effect of one independent variable depends on the particular level of another independent variable.

Why are interactions not obtained in simple experimental designs?

Because only one independent variable is manipulated.

How can interactions be visually represented?

They can be seen easily when the means for all conditions are presented in a graph.

What are the possible outcomes when analyzing a 2x2 factorial design?

There may or may not be significant main effects for independent variable A and B, and there may or may not be a significant interaction.

What statistical method is used to assess the significance of main effects and interactions in factorial designs?

Analysis of variance (ANOVA).

What is the difference between independent groups and repeated measures designs?

Independent groups require different participants for each condition, while repeated measures use the same participants across all conditions.

What is a mixed factorial design?

A design that includes both independent group (between-subjects) and repeated measures (within-subjects) variables.

How can complexity be increased in factorial designs?

By increasing the number of levels of one or more independent variables.

What does a 2x3 design consist of?

Two independent variables, with one having two levels and the other having three levels, resulting in six conditions.

What is the outcome of a 2x2x2 factorial design?

It has three variables, each with two levels, resulting in eight conditions.

What is a potential drawback of designs with many independent variables?

They can become needlessly complex, require large numbers of participants, and yield results that are difficult to interpret.