Two-way factorial example
Student experiment (Yu-Pei Chang): A study of toy cars
Response
Distance (in cm) traveled until car comes to a stop.
Primary factors
- ramp: A ramp is in fact a 3-ring binder. One, two, or three
1-inch binders are stacked.
- car: Two different toy cars are studied: a large and a small one.
Our initial goal is to be able to detect variations of plus or minus 10 cm.
(effect-size SD = 5 cm).
Random factors
- RESIDUAL = REP(ramp*car):
Each test run involves choosing a car and a ramp slope,
releasing the car, and measuring how far it goes.
Estimated residual SD is 13.3 based on pilot data.