<P> The participants are the individuals who sign up for the speed dating event and interact with each of the 9 individuals of the opposite sex . There are 10 males and 10 female participants . After each date, they rate on a scale of 0 to 100 how much they would like to have a date with that person, with a zero indicating "not at all" and 100 indicating "very much". </P> <P> The repeated measures are looks, which consist of three levels (very attractive, moderately attractive, and highly unattractive) and the personality, which again has three levels (highly charismatic, moderately charismatic, and extremely dull). The between - subjects measure is gender because the participants making the ratings were either female or male . </P> <P> When running an analysis of variance to analyse a data set, the data set should meet the following criteria: </P> <Ol> <Li> Normality: scores for each condition should be sampled from a normally distributed population . </Li> <Li> Homogeneity of variance: each population should have the same error variance . </Li> <Li> Sphericity of the covariance matrix: ensures the F ratios match the F distribution </Li> </Ol>

What is the correct formula for between groups degrees of freedom