Final answer:
The degrees of freedom used for examining a simple main effect from a two-factor ANOVA with two levels in each factor and n = 7 per condition would be df = 1, 24.
Step-by-step explanation:
When examining a simple main effect from a two-factor ANOVA with two levels in each factor and n = 7 individuals in each treatment condition, you'll be using specific degrees of freedom (df) for the analysis. For the simple main effect within a factor, df between groups (sometimes called df numerator) is generally the number of levels in the factor minus one. Since there are two levels, df between groups is 2 - 1 = 1. For df within groups (or error df, sometimes called df denominator), it is calculated by taking the total number of subjects minus the number of groups. In this case, with 4 groups (2 levels in factor A times 2 levels in factor B) and 7 subjects per group, df within groups = 4 * 7 - 4 = 28 - 4 = 24. Hence, the degrees of freedom for the simple main effect analysis would be df = 1, 24.