Unit 9: Group Experimental Research: Factorial Designs

Question 1

ex post facto design

Answer 1

In a multi-factorial design, if neither/no independent variable can be manipulated (ex. age and gender)

Question 2

quasi-factorial design

Answer 2

In a multi-factorial design, when one variable can not be manipulated (ex. gender and prescribed hours of exercise)

Question 3

factorial design

Answer 3

An experimental design in which there are more than one independent variable simultaneously tested to see their independent and combined effect.
* All possible combinations of selected levels are tested.

Question 4

main effect

Answer 4

When one of the IVs in a multi-factorial design has a statistically significant impact on the DV.
In a MFD, this is determined by averaging the effects of that variable over all levels of the other IV(s).

Question 5

interaction effect

Answer 5

The effect that one variable has on another - when the effect of one depends on the level of another.
If there’s an interaction, main effects can’t be discussed without discussing the interaction.

Question 6

mixed design

Answer 6

Some factors are within-subject and some are between-subject.

Question 7

What are the advantages of using factorial designs?

Answer 7

• you can better understand the role of IVs by studying their effects on each other - good when complex relationship of factors is suspected
• controls for possible confounding variables
• sometimes easier and cheaper than creating a whole other experiment

Question 8

How many cells (combinations) are there in a 2 x 3 x 4 factorial design?

Answer 8

24

Question 9

How can one tell graphically if there is an interaction effect between two variables?

Answer 9

If the lines are not parallel - either cross or would cross if continued off the chart.

Question 10

What are the common types of interactions in psychological research?

Answer 10

Antagonistic: One variable reverses the effect of another
Synergistic: one variable enhances the effect of another
Ceiling-effect: One variable causes a smaller effect in the other variable than if absent.

Question 11

What is the difference among within-subjects, between-subjects, and mixed factorial designs?

Answer 11

WIS: each person experiences all conditions
BS: each person experiences only one condition
MFD: each person experiences all levels of one condition, and only one level of another(s)