interaction between within subjects and qVars in 3dMVM

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1

AFNI version info (afni -ver): Version AFNI_23.0.00 'Commodus'

Hello!

I am trying to compute an interaction using 3dMVM. I have 3 within subject variables (load, presabs, and Hb), each with two levels (2x2x2).

I have a covariate (TCShape) that I would like to plug into the model using qVars. The code is below:

3dMVM -mask AS_mask60.nii -prefix TCCov -jobs 4 \
-GES \
-resid TCov_RESID.nii \
-wsVars "Load*PresAbs*Hb" \
-qVars "TCShape" \
-SS_type 2 \
-dataTable     \
Subj TCShape Load PresAbs Hb InputFile \
S103 0.55 low abs HbO S103_AS50_cond1_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 low pres HbO S103_AS50_cond2_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 high abs HbO S103_AS50_cond3_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 high pres HbO S103_AS50_cond4_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 low abs HbR S103_AS50_cond1_Unmasked_deoxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 low pres HbR S103_AS50_cond2_Unmasked_deoxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 high abs HbR S103_AS50_cond3_Unmasked_deoxy_ND_To_Atlas_ClipToBrain.nii.gz \
S103 0.55 high pres HbR S103_AS50_cond4_Unmasked_deoxy_ND_To_Atlas_ClipToBrain.nii.gz \
S104 0.45 low abs HbO S104_AS50_cond1_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \
S104 0.45 low pres HbO S104_AS50_cond2_Unmasked_oxy_ND_To_Atlas_ClipToBrain.nii.gz \

The model runs without issue, however, the results only show the interactions of my within subjects variables and seems to ignore the qVars variable.

How can I get an interaction to show up with my covariate?

Thank you,

Hollee

2

Hollee,

I assume that TCShape does not vary within individuals. Add the following to your 3dMVM script

-bsVars "TCShape" \

Also, it might be slightly preferable to have

-SS_type 3 \

Gang Chen

3

Hello Gang!

Thank you for your reply,

I implemented both of your suggestions to my script but I still do not see the interaction.

3dMVM -mask AS_mask60.nii -prefix TCCov -jobs 4 \
-GES \
-resid TCov_RESID.nii \
-wsVars "Load*PresAbs*Hb" \
-qVars "TCShape" \
-bsVars "TCShape" \
-SS_type 3 \

Screenshot 2023-12-02 at 10.00.35 PM
Screenshot 2023-12-02 at 10.00.35 PM1970×912 324 KB

4

I'm uncertain about why the updated script didn't function as expected. If you can't resolve the issue, I might need you to provide the data and script for further diagnosis.

Gang Chen

5

Hello Gang,

What would be the best way to share the data to you?

Thank you again for your help,

Hollee

6

I just sent you an email outlining a method for sharing your data and script.

Gang Chen

7

Hi Gang,

Thank you so much for your time. I figured out why it was not popping up in afni.

After simply restarting afni, all the interactions showed up.

Thank you again,

Hollee