Chapter 10: Complex Experimental Designs

Question 1

Better Than Average Effect (BTA or BEA)

Answer 1

Definition: The difference between

People tend to rate themselves more favorably than they rate other people.

Question 2

When should you increase levels?

one IV, with 3+ levels

Answer 2

1. If there is reason to predict a non-linear relationship
2. In order to test a specific hypothesis
3. The study is exploratory

Question 3

Factorial Design: Definition

Answer 3

An experiment with more than one IV where all levels of each IV are combined with all levels of the other IV.

ex: 2x2 factorial design has 2 IVs, each with 2 levels. So, there would be 4 total conditions.

Question 4

Why use a Factorial Design?

Answer 4

Allows investigation of the separate main effects and interaction of two or more independent variables

Question 5

Types of Factorial Designs

Answer 5

1. Between-Subjects Factorial Design
2. Within-Subjects Factorial Design
3. Mixed Factorial Design

Question 6

Between-Subjects Factorial Design

Answer 6

Each participant goes through only one combination of levels of variables

• All variables are manipulated between-subjects.

Question 7

Within-Subjects Factorial Design

Answer 7

All participants go through all levels of every variable.

*All variables are manipulated within-subjects.

Question 8

Mixed Factorial Design

Answer 8

At least one variable is manipulated via within-subjects and at least one variable is manipulated via between-subjects.

Question 9

Factorial Design - Effects

Answer 9

1. Simple (main) Effect
2. Main Effect
3. Interaction

Question 10

Simple (main) Effect

Answer 10

The effect of one IV at a specific level of another IV

If there is NOT interaction, simple effects will not be different from each other (usually)

Question 11

Main Effect

Answer 11

The direct effect of an IV on a DV

Main effects may not be to interpret when an interaction is present.

Question 12

Interaction

Answer 12

When the effect of one IV changes based on the level of another IV

Interaction = a difference between differences

Question 13

To Understand Interactions first…

Answer 13

1. first looking at simple effects.
2. Then compare the simple effects to each other.
3. If they are not the same, there may be an interaction.

Question 14

Describing an Interaction

Answer 14

a) State the effect at one level of an IV (one simple effect)

b) State the effect at the other level of an IV (other simple effect)

c) COMPARE the two statements (the two simple effects)

Question 15

How many Effects In a 2x2 Factorial Design

Answer 15

• 4 simple effects – but typically only report 2 to illustrate a significant interaction
• 2 main effects – important to report both.
• 1 interaction – one interaction with two different “angles”

Question 16

Assigning Participants to Conditions: Within-subjects design

Answer 16

The same person participates in every condition

Within-Subjects 2x2 Factorial Design:

• Four total conditions, but only one group of participants needed.
• If each condition needs 10 people, you would only need 10 different participants total. n=10

Question 17

Assigning Participants to Conditions: Between-subjects design

Answer 17

Different groups of participants are assigned to each of the conditions.

Ie: Between-Subjects 2x2 Factorial Design:

• Four total conditions. Thus, four different participant groups.
• If each condition needs 10 people, you would need 40 different participants total. n=40

Question 18

Assigning Participants to Conditions: Mixed Factorial Design

Answer 18

Experiment includes both Between and Within groups designs, so one IV would need different participants for each condition, and the other would only need one group of participants

Mixed 2x2 Factorial Design: (IV-a = between, IV-b = within)

• Four conditions total. 2 conditions will require separate participant groups, while 2 conditions will only need one.
• If each group needs 10 participants, IV-a would need a total of 20 participants & IV-b would need a total of 10
• Grand total of n=30

Question 19

Interaction “angles”

Answer 19

2 ways to look at one Interaction:

1. Does the effect of IV-a depend on the level of IV-b?
2. Does the effect of IV-b depend on the level of IV-a?

Question 20

Which “angle” is best?

Answer 20

Use the angle that directly address’ the research question

But, both help understand the interaction.