How can I calculate and report degrees of freedom for repeated mesure ANOVA?
I have 48 observations N=48 and 2 factors of 3(P) and 8(LA) levels.
I calculate degrees of freedom as follows:
dF P = a-1= 2
df LA = b-1= 7
df LA*P =(a-1)(b-1)= 14
Error dF P = (a-1) (N-1) = 94
Error dF LA = (b-1) (N-1) = 329
Error dF P*LA = (a-1)(b-1)(N-1) = 658
My JASP analysis gave me these results:
Within Subjects Effects
Cases Sum of Squares df Mean Square F p η²
P 1.927 2 0.964 33.9 < .001 0.120
P*LA 8.450 14 0.604 21.2 < .001 0.528
Residuals 0.454 16 0.028
Can I write P : F(2,14)= 33.9
and P*LA: F(14, 658) =21.2 ???
Or is it P: F(2, 16)=33.9
P*LA: F(14, 16) =21.2 ???
Thanks to anyone who would like to answer
Paola Manzo You have 3 different F-tests
1. Factor 1 (Main effect)
2. Factor 2 (Main effect)
3. Factor 1 x Factor 2 (Interaction effect)
Since there are 3 different F-tests, the degrees of freedom will be different for each test. Based on your output, they would be as follows:
1. F(2, 94) (Factor 1)
2. F(7, 329) (Factor 2)
3. F(14, 658) (Interaction)
*The first value in the parentheses corresponds to the degrees of freedom for the independent variable. The second value corresponds to the degrees of freedom for the error term.
Hello Paola,
If both factor "P" and factor "LA" are both fixed-effects, within-subjects factors (e.g., repeated measures factors), then Blaine Tompkins' answer is correct for the respective tests: P, LA, & P*LA.
If the design is different than this, you'll need to explain in more detail to get the right feedback.
Good luck with your work.
If the number of factor is 3 and number of level is 8, the error degrees of freedom is 14.
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