CH 11 - Factorial Designs

Question 1

Factorial Designs

Answer 1

Allows us to examine complex relationships among variables in a single study

• The effects of more than one IV on a given DV
• The interactions between the IVs - combined effects

*If more than one IV in a study we refer to them as factors

High ecological (real world) validity

Question 2

Digits

Answer 2

The number of digits indicates how many factors there are in your study; and the actual value of each digit indicates how many levels there are for each factor.

Question 3

Main Effects

Answer 3

Treatment differences between levels of a given factor

• Main effect for Factor A
• Main effect for Factor B

Question 4

Interaction effects

Answer 4

Combined effect of factors
- an interaction occurs when the effect of one factor depends on another.

Question 5

Hypotheses

Answer 5

2x2 = 3 hypotheses

• M Factor A has an effect on the dependent variable.
• M Factor B has an effect on the dependent variable.
• I The effect of Factor A on the dependent variable depends on Factor B.

Question 6

Interpreting Results

Answer 6

1. Look for main effects first. Compare the column means for Factor A.

If means are identical, no main effect for Factor A

2. Compare the row means to determine main effect for Factor B.

Means not identical; main effect for Factor B.

3. To look for interactions, check if difference in row means (e.g., d =10) is consistent across columns.

Differences identical; no interaction.
No differential = parallel

Question 7

Stating results

Answer 7

Address interactions first before considering main effects
Your statement should include the phrase “depends on”

The effect of Factor A on the dependent variable depends on Factor B.

If there is no interaction, discuss the main effects.

Question 8

3 Types

Answer 8

• Pure factorial: between-groups OR within-groups
• Mixed factorial: between-groups + within-groups
• Combined factorial: experimental + non- or quasi- experimental (participant or time variable)

Question 9

Pure Factorial

Answer 9

Between groups design
- different groups of participants are randomly assigned to each cell of the design

Question 10

Mixed Factorial

Answer 10

Combination of between group and within group factors

Question 11

Combined Factorial

Answer 11

Combination of experimental (manipulated) and non- or quasi-experimental (participant or time) factors

Limitations - One factor not manipulated limits the ability to make casual statements.
*Assignment bias is present
*Internal validity is low (lack of manipulation and possible confound)
**External validity is good as it’s more representative of real life

Question 12

Higher Order Factorials

Answer 12

More than 2 factors

3 factors = one 3-way interaction and three 2-way interactions

Question 13

Summary

Answer 13

Highly efficient designs which allow researchers to study:
- effect of many factors simultaneously
- interactions among factors

High external validity (ecological validity)

Complex nature provides real advantages, but also some challenges (especially interpretation).

Also, the number of possible confounds are multiplied by the number of factors considered in the study.