3dMVM quantitative variable

AFNI Message Board
1

Hi experts,

I am using 3dMVM to see how age effect fMRI as a quantitative variable. I got results Age F from the code. But F scores are all positive. I am wondering if it possible to get a β coeffector from 3dMVM? Or some effector could show the data is increasing or decreasing with age.

Thank you.

My code:


3dMVM -prefix Aud_glt3 \
-bsVars "Group*Age*Risk" \
-qVars "Age,Risk" \
-num_glt 3                         \
-gltLabel 1 Group -gltCode  1 'Group : 1*Singr -1*Contr'            \
-gltLabel 2 GroupRisk -gltCode  2 'Group : 1*Singr -1*Contr  Risk:'          \
-gltLabel 3 GroupAge -gltCode 3 'Group : 1*Singr -1*Contr  Age:'          \
-dataTable \
Subj Group Age Sex Risk InputFile \
S002 Singr 70 1 1 S002.rs.AudSeederrts.nii'[0]'\
......
2

You can add the following to obtain the directionality of age effecct:

-gltCode t ‘Age :’ \

Also, you need to add a space after Risk and Age on the following two lines:

-gltLabel 2 GroupRisk -gltCode 2 ‘Group : 1Singr -1Contr Risk:’
-gltLabel 3 GroupAge -gltCode 3 ‘Group : 1Singr -1Contr Age:’ \

3

Thank you Gang! I got two sub-bricks ‘Age’ and ‘Age t’. But I am wondering if I set age as a quantitive variable, how the t test runs here?

I got the exact same results after adding a space. Did I add at the right places?


-gltLabel 2 GroupRisk -gltCode 2 'Group : 1*Singr -1*Contr Risk: ' \
-gltLabel 3 GroupAge -gltCode 3 'Group : 1*Singr -1*Contr Age: ' \
-gltLabel 4 Age -gltCode 4 'Age :' \

Thank you!

Xiyue

4

The following two lines

-gltLabel 2 GroupRisk -gltCode 2 'Group : 1Singr -1Contr Risk: ’
-gltLabel 3 GroupAge -gltCode 3 'Group : 1Singr -1Contr Age: ’ \

should change to

-gltLabel 2 GroupRisk -gltCode 2 'Group : 1Singr -1Contr Risk : ’
-gltLabel 3 GroupAge -gltCode 3 'Group : 1Singr -1Contr Age : ’ \

But I am wondering if I set age as a quantitive variable, how the t test runs here?

The t-test for age is for the slope or marginal effect: the amount of change in the response variable when age increases by 1.

5

Hi Gang,

Thank you for your reply.
I still think the results are the same in sub-bricks GroupAge and GroupAge t, including the clusters location and voxel numbers. Now my code is like this:


-num_glt 4 \
-gltLabel 1 Age -gltCode 1 'Age :' \
-gltLabel 2 Group -gltCode 2 'Group : 1*Singr -1*Contr' \
-gltLabel 3 GroupRisk -gltCode 3 'Group : 1*Singr -1*Contr Risk : '\
-gltLabel 4 GroupAge -gltCode 4 'Group : 1*Singr -1*Contr Age : '\

The t-test for age is for the slope or marginal effect: the amount of change in the response variable when age increases by 1.

If I am correct, the result of the Age t is smilar to the result of 3dRegAna -tcoef. Right?

Thank you.

Xiyue

6

If I am correct, the result of the Age t is smilar to the result of 3dRegAna -tcoef. Right?

If you built the same model between 3dMVM and 3dRegAna, the result should be close to each other.

7

Thank you very much!

Xiyue