There are three questions that you can ask and answer with this type of analysis: Is there a difference in weight loss between two levels of exercise program, high impact and low impact? Is there a difference in weight loss between two levels of gender, male and female? Is the effect of being in the high- or low-impact program different for males or females? Questions 1 and 2 deal with the presence of main effects (the effect of each independent variable by itself), whereas Question 3 deals with the interaction between the two factors.
