Degrees of Freedom
In order to calculate the degrees of freedom for between-subjects effects, dfBS = R – 1, where R refers to the number of levels of between-subject groups.
In the case of the degrees of freedom for the between-subject effects error, dfBS(Error) = Nk – R, where Nk is equal to the number of participants, and again R is the number of levels.
To calculate the degrees of freedom for within-subject effects, dfWS = C – 1, where C is the number of within-subject tests. For example, if participants completed a specific measure at three time points, C = 3, and dfWS = 2.
The degrees of freedom for the interaction term of between-subjects by within-subjects term(s), dfBSXWS = (R – 1)(C – 1), where again R refers to the number of levels of the between-subject groups, and C is the number of within-subject tests.
Finally, the within-subject error is calculated by, dfWS(Error) = (Nk – R)(C – 1), in which Nk is the number of participants, R and C remain the same.
Read more about this topic: Mixed-design Analysis Of Variance
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