Discussion:
Experimental Design
In an experiment designed to examine the effects of dieting and exercise on weight loss, subjects were randomly assigned to one of four conditions: (1) both dieting and exercise, (2) dieting but no exercise, (3) exercise but no dieting, and (4) neither dieting nor exercise. Results indicated that subjects not on a diet lost only three pounds whether or not they exercised. However, subjects who dieted lost 15 pounds if they exercised and 8 pounds if they did not exercise.
Questions:
a) Is there a main effect for dieting? If so, describe the effect.
b) Is there a main effect for exercise? If so, describe the effect.
c) Is there an interaction effects? If so, describe the effect.
d) Is this a true experiment? Why, or why not?