Hi All,

I am a graduate student trying to finish my dissertation and rejoin society and I’m trying to set up both a design matrix and contrast matrix for a 2 factor (age and cognition) ANOVA with 3 levels each (age:young, middle aged and old ; cognition: low, average and high).

I’ve used the FSL guidelines and for the design matrix I’ve assigned age to be “A” and cognition to be “B” and grouped the animals as follows:

A1B1 A1B2 A1B3 A2B1 A2B2 A2B3 A3B1 A3B2 A3B3

Can fixelcfestats be used for such an ANOVA design?

If yes then is this the correct set of contrasts for the main effects of A and B as well as the interaction between the 2.

Contrast Matrix:

Main effect of A:

for A1-A2: 1 1 1 -1 -1 -1 0 0 0

for A1-A3: 1 1 1 0 0 0 -1 -1 -1

Main effect of B:

for B1-B2: 1 -1 0 1 -1 0 1 -1 0

for B1-B3: 1 0 -1 1 0 -1 1 0 -1

Interaction effects:

for A1-A2 across B: A1B1-A2B1 = A1B2-A2B2 = A1B3-A2B3 so A1B1-A2B1-A1B3+A2B3 =A1B2-A2B2-A1B3+A2B3=0

1 0 -1 -1 0 1 0 0

0 1 -1 0 -1 1 0 0 0

for A1-A3 across B: A1B1-A3B1=A1B2-A3B2=A1B3-A3B3 so A1B1-A3B1-A1B3+A3B3 = A1B2-A3B2-A1B3+A3B3 =0

1 0 -1 0 0 0 -1 0 1

0 1 -1 0 0 0 0 -1 1

for B1-B2 across A: B1A1 -B2A1 = B1A2-B2A2 = B1A3-B2A3 so B1A1-B2A1 -B1A3+B2A3 = B1A2-B2A2-B1A3+B2A3 = 0

1 -1 0 0 0 0 -1 1 0

0 0 0 1 -1 0 -1 1 0

for B1-B3 across A: B1A1-B3A1=B1A2-B3A2=B1A3-B3A3 so B1A1-B3A1-B1A3+B3A3 = B1A2-B3A2-B1A3+B3A3=0

1 0 -1 0 0 0 -1 0 1

0 1 0 0 0 -1 -1 0 1

Thank you

Loi Do