3dMVM: help with glfCode and gltCode

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1

Hi,

I’m trying to run 3dMVM to see if there is significant difference between groups (G1, 2, 3, 4) in terms of neural activation during anticipation of monetary gain. I choose 3dMVM instead of 3dANOVA because we have unbalanced sample. I was wondering what is the accurate way to set up glfCode and gltCode to run F-test to test for the overall group difference, as well as post-hoc ttests to test the difference between the groups.

Below is what I had in the script:

-num_glf 1
-glfLabel 1 group -glfCode 1 ‘group : 1G1 & 1G2 & 1G3 &1G4’
-num_glt 6
-gltLabel 1 G2-G1 -gltCode 1 ‘group : 1G2 - 1G1’
-gltLabel 2 G3-G1 -gltCode 2 ‘group : 1G3 - 1G1’
-gltLabel 3 G4-G1 -gltCode 3 ‘group : 1G4 - 1G1’
-gltLabel 4 G3-G2 -gltCode 4 ‘group : 1G3 - 1G2’
-gltLabel 5 G4-G2 -gltCode 5 ‘group : 1G4 - 1G2’
-gltLabel 6 G4-G3 -gltCode 6 ‘group : 1G4 - 1G3’ \

I have tried running the script, but received an error message saying: “Inappropriate coding in test No.1!”

Best,
Tien

2

Tien,

Try the script again after removing the extra space after the minus sign (‘-’) in each of the following lines:

-gltLabel 1 G2-G1 -gltCode 1 ‘group : 1G2 - 1G1’ \
-gltLabel 2 G3-G1 -gltCode 2 ‘group : 1G3 - 1G1’ \
-gltLabel 3 G4-G1 -gltCode 3 ‘group : 1G4 - 1G1’ \
-gltLabel 4 G3-G2 -gltCode 4 ‘group : 1G3 - 1G2’ \
-gltLabel 5 G4-G2 -gltCode 5 ‘group : 1G4 - 1G2’ \
-gltLabel 6 G4-G3 -gltCode 6 ‘group : 1G4 - 1G3’ \

3

Hi Gang,

Thank you very much for your response. Removing the extra space solved the issue.

I have a related questions about glfCode in 3dLME. The -help output of 3dLME said that:

the coding


'Condition : 1*A -1*B & 1*A -1*C Emotion : 1:pos'

tests the main effect of Condition at the positive Emotion

Is this supposed to be


'Condition : 1*A -1*B & 1*A -1*C Emotion : 1*pos'

?

Because I’ve tried the coding from the -help output and get the following error message:

Error in seq.default(2, length(sepTerms), 2) :
wrong sign in ‘by’ argument
Calls: process.LME.opts → gl_Constr → glfConstr → seq → seq.default
Execution halted

Best,
Tien

4

Tien, thanks for pointing out the typo!