-
AuthorPosts
-
02/10/2019 at 7:03 PM #6599rubenscuryParticipant
Hi colleagues,
I’m trying to compare variables between 2 groups in the Lead Group (for example, bad vs good responders on motor outcomes in Parkinson’s disease). Patients were settled in the group I or II. When I run the group comparison (two sample t-test) after prepare stats, it appears a screen with “normalized volume intersections, left hemisphere” for example, and “t-value=NaN, p-value=Nan”….I don’t know what is going wrong….Did anybody succeed with group comparison t-test analysis?Many thanks
Rubens02/11/2019 at 9:51 AM #6603andreashornKeymasterHi Rubens,
good to hear from you – could it be that the sample size is too small for a t-test? What is your N of the two groups?
Once you click the button, the raw data should appear in your Matlab workspace as well, so you can easily export and do stats elsewhere, as well.Hope that helps!
Best, Andy
03/15/2019 at 10:14 PM #6985rubenscuryParticipantThanks Andy,
I am comparing group 1 (N=20) vs group 2 (N=10)….it still appears the following message in the matlab workspace:
Volume Intersections, both hemispheresh =
NaN
p =
NaN
ci =
NaN
NaNand so on….
The correlation is working very well, but the group comparison I am not sure what is happening…
Many thanks
Rubens03/16/2019 at 12:46 PM #6988andreashornKeymasterHi Rubens,
maybe your regressor is set up incorrectly. It should be all ones for group 1 and all zeros for group 2.
So assume you have e.g. 5 top responders and 5 poor responders and want to run a paired t-test on their VTA intersections with the STN, then you would add a vector like
[1
1
1
1
1
0
0
0
0
0];
as the regressor. Then click on the group comparison button.And then it should work.
Best, Andy
03/16/2019 at 12:47 PM #6989andreashornKeymaster(of note, the word “regressor” is wrong here, it has some historic reasons why I’m used to reference the variables entered into lead group as “regressors”). In this case, it’s basically just a variable that codes for the groups.
03/16/2019 at 2:29 PM #6990rubenscuryParticipantVery nice Andy, thanks a lot
I am also trying to change the “brain parcellation” in the Lead Group. For exemple, move from AICHA to Harvard Oxoford…..
In the Lead Group, all the patients and the variables are already set. But when I change in the link “which brain parcellation to use:” from AICHA to Harvard Oxoford and run “Prepare Stats”, in the “fiber count to” still appears the AICHA parcellation (G_Frontal_Sup_Orb…etc…)…i.e. it is not changing the brain area….Would you have any insight for what is going wrong?
Again, thanks for your attention
Best
Rubens03/16/2019 at 2:34 PM #6991andreashornKeymasterNo it should update like that.
You probably could update to 2.2 and test again?Best, Andy
03/16/2019 at 3:30 PM #6992andreashornKeymasterHi Rubens,
I also just noticed that there was a serious bug in the ttest functionality in the “normalized” VTA reports.
https://github.com/netstim/leaddbs/commit/54fdc91f0570d442388f6030f58a56c9337ccf0f#diff-c406b0ce9f31d9fc6834ffef4b9e7f78R917
See this edit – if you need it now would need to change lines 917, 920 and 923 accordingly (or wait for the next update).Thanks! Andy
03/16/2019 at 6:06 PM #6993rubenscuryParticipantThanks Andy,
The “brain parcellation” problem I solved, it is working normally…
The “t-test” issue I’ll try later and see….
Best
Rubens -
AuthorPosts
- The forum ‘Support Forum (ARCHIVED – Please use Slack Channel instead)’ is closed to new topics and replies.