Chapter 8: Experimental designs: Between-subjects design

Introduction to between-subjects experiments

Applications and statistical analyses of between-subjects designs

Individual differences as confounding variables

Other threats to internal validity of between- subjects experimental designs

Individual differences and variablity

Limiting confounding by individual differences

Review of the experimental research strategy

Characteristics of between-subjects designs

Independent scores

Advantages and disadvantages of between-subjects designs

Individual differences

Other confounding variables

Confounding from individual differences

Confounding from environmental variables

Equivalent groups

Random assignment (Randomization)

Matching groups (Matched assignment)

Holding variables constant or restricting range of variability

Summary and recommendations

Differences between treatments and variance within treatments

Minimizing variance within treatments

Stadardize procedures and treatment settings

Limit individual differences

Random assignment and matching

Sample size

Summary and recommendations

Differential attrition

Communication between groups

Two-group mean difference

Comparing means for more than two groups