Instacorr question

Dear AFNI users,

I am new to afni. I am trying to use Instacorr to compute group differences in seed connectivity. I am able to make instacorr show me connectivity in a single subject; however, I do not know how to make it show me group differences? Are there any instructions of how to make it do that? Mainly, I do not know how we assign the groups and how we make it give a group results.

Thanks a lot for the help.


Hi Paul,

For a group analysis, first pre-process the data,
then prepare for the group analysis by running
3dSetupGroupInCorr, then run 3dGroupInCorr. For a
mild resting state example, see “RESTING STATE NOTE”
under the output from -help, and review
the included used of 3dGroupInCorr.

Also, see 3dGroupInCorr -help.

Note that 3dGroupInCorr generate either live group
results, or results using the -batch mode forms of
the command, appropriate for scripting a formal

  • rick

Great thanks Rick! this is very helpful.


Dear all,

I am running 3dSetupGroupInCorr ; I keep getting “FATAL ERROR: Write to ‘’ failed – disk full? permission?”

I do have plenty of space on the disk and I do have permissions. I had already run the command on a different group of scans (one of my groups for the ttest) and it worked.

Any tips?


From that directory, what is the output of these commands?

df -h .
ls -ld .
  • rick

Hi Rick

df -h

Filesystem Size Used Avail Use% Mounted on
50G 25G 23G 53% /
tmpfs 16G 1.2M 16G 1% /dev/shm
/dev/sda1 477M 85M 367M 19% /boot
1.8T 1.3T 401G 77% /data11
/dev/sdb1 1.8T 196M 1.7T 1% /data12
/dev/sdc1 1.8T 1.6T 130G 93% /data13
dumbledore:/data4 809G 651G 118G 85% /data4
dumbledore:/data5 917G 805G 66G 93% /data5
potter:/data6 1.8T 1.5T 163G 91% /data6
potter:/data7 1.8T 714G 969G 43% /data7
1.8T 1.4T 298G 83% /data
1.8T 1.4T 298G 83% /home
hogwarts:/data9 4.5T 3.3T 1.1T 77% /data9
hogwarts:/data10 4.5T 4.2T 58G 99% /data10
madeye:/data2 3.2T 2.6T 414G 87% /data2
madeye:/data3 3.2T 2.6T 414G 87% /data3
krum:/data14 1.8T 473G 1.2T 29% /data14
krum:/data15 1.8T 278G 1.5T 16% /data15
krum:/data16 1.8T 199M 1.7T 1% /data16
/dev/sdd1 4.5T 4.0T 339G 93% /mnt/backup1

ls -ld

drwxrwxrwx 2 paulg dslab 4096 Jul 25 22:10 .




By the way I am working in the directory



Actually, when I split the data in half…it works on each half . Could it be a RAM issue rather than disk space?