PSYB70H3 - Unit 7

Factorial Designs

Experimental setups used to investigate two or more independent variables (IVs) to understand how they interact to affect a dependent variable (DV).

Independent Variables (IVs)

Factors manipulated by the researcher.

Participant Variables

Characteristics of the participants that are not manipulated.

Contextual Variables

Situational factors affecting the study.

Moderators

Conditions under which an IV affects the DV.

Crossing Factors

Examining all combinations of IVs to evaluate their impact on the DV.

Interactions

Occur when the effect of one IV varies depending on another IV.

Main Effects

The impact of a single IV on the DV, without considering other IVs.

Interaction Effects

Combined effects of two or more IVs on the DV.

Two-Way Factorial Designs

Assess effects of two factors.

Three-Way Factorial Designs

Investigate effects of three factors.

2x2 design

Two factors, each with two levels (e.g., Dosage and Time).

3x2 design

Two factors, one with three levels and the other with two levels.

Total number of experimental conditions

Multiply the numbers to get the total number of experimental conditions (e.g., 2x2 = 4 conditions, 3x2 = 6 conditions).

Null Effect

Indicates no main effects or interactions.

One Main Effect

Indicates one IV significantly influences the DV.

Additive Effects

Both IVs affect the DV independently.

Cross-Over Interactions

The effect of one IV reverses across levels of another IV.

Spreading Interactions

The strength of one IV's effect varies across levels of another IV.

Analysis of Variance (ANOVA)

Compares means across groups.

F-Test

Statistic used in ANOVA.

p-Value

Indicates statistical significance (typically p<.05).

Effect Size Indicators

Such as Eta-squared (η²) and Cohen's d.

Planned Contrasts

Follow-up analyses for specific effects.

Between-Subjects Experiments

Each participant experiences only one condition.

Within-Subjects Experiments

Each participant is tested under all conditions.

Random Assignment

Randomly assigning participants to conditions to control for extraneous variables.

Carryover Effects

Influence of one condition affects responses in subsequent conditions.

Counterbalancing

Technique to control order effects by varying the order of conditions.

Complete Counterbalancing

All possible orders tested equally.

Latin Square Design

Each condition appears in each position once.

Factorial Design in Psychology

A factorial design involves multiple IVs to assess their effects on one or more DVs.

Main Effects

Effect of one IV on the DV averaged across levels of the other variable.

Interactions

Effect of one IV depends on another IV's level.