III. (True) experimental design 

A. Levels and variables  

 

 

 

B. Simple, two-group design

•  experimental group 

•   control group

C. How do we assign subjects?

1. Random assignment

2. Correlated assignment

a. matched pair

b. natural pairs

c. repeated measures

D. Repeated measures designs

 

 

• Advantages and disadvantages

 

E. Increasing the complexity of designs

1. Increase the number of levels of a variable

2. Increase the number of dependent variables

3. Increase the number of Independent Variables – Factorial Designs

 IV. Factorial Designs

• Increasing the complexity by increasing the number of Independent Variables 

A. Advantages of factorial designs

B. Main effects vs. interaction effects

MAIN EFFECTS – the effects of one variable, ignoring (averaged across) the other

INTERACTION EFFECTS – the effects of the variables together

Does one variable CHANGE the effects of another?

C. Interaction effects 

an example:...

1. What are some hypotheses we could make?

2. Possible outcomes:

• Main Effects ONLY

• Interaction Effects

3. What would both main effects and interaction effects look like?

D. Interpreting Interaction Effects

   DISCUSSION/ACTIVITY (HOMEWORK 8 - completed in class)

 

  E. Statistics for multiple group means (ANOVA)