Chapter 10

Chapter 10 – Designing Experiments

Causality
What is the cause of phenomena?
3 Conditions of internal validity:
1. X comes before Y (antecedence)
2. X and Y are in the same space and time (contiguity)
3. Z is explained away (necessary connection)

Experiments
Prediction and control…independent variable (we manipulate), dependent variable (we measure).
Pre-test -> Treatment -> Post-test
Pre-test -> Control -> Post-test
*Randomly assigning participants to treatment and control groups. This is not random sampling a population. Both groups are equivalent.
External validity: generalization from lab to real world.
Internal validity goes up (control goes up) then external validity goes down (generalizability to real life)

Between groups and repeat measure are the basic experimental design.
Time related effects are the huge critic against repeated measure cause. (pp 279-285).