# A question which is about how to minus two conditions in freesurfer **URL:** \ **Category:** Mailing List Archive (read-only)\ **Tags:** list-archive\ **Created:** [February 24, 2011, 11:14am UTC](https://mne.discourse.group/t/a-question-which-is-about-how-to-minus-two-conditions-in-freesurfer/288 "2011-02-24T11:14:30Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [February 24, 2011, 11:14am UTC](https://mne.discourse.group/t/a-question-which-is-about-how-to-minus-two-conditions-in-freesurfer/288/1 "2011-02-24T11:14:30Z")
Hi 🙂 I am so sorry to bother you all these days , i use freesurfer and mne to analyze my MEG data but now , i have a problem as follow : 1.how can I minus two conditions , cus I wanna see the difference between two conditions? EX: (deviant condition - standard condition) It confused me for long time , hope anyone can help me , thx Eddid -------------- next part -------------- An HTML attachment was scrubbed... URL: [http://mail.nmr.mgh.harvard.edu/pipermail/mne\_analysis/attachments/20110224/0e53937d/attachment.html](http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20110224/0e53937d/attachment.html) ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [March 17, 2011, 7:27pm UTC](https://mne.discourse.group/t/a-question-which-is-about-how-to-minus-two-conditions-in-freesurfer/288/2 "2011-03-17T19:27:59Z")
Hi, > these days , i use freesurfer and mne to? analyze my? MEG data > but now , i? have a? problem as? follow : > 1.how can?I minus two conditions , cus I wanna see the? difference between > two? conditions? EX:? (deviant condition? -? standard condition) what is your setup? you want to compare within one subject? in a group of subjects? if it's just one subject, an easy solution consists in loading the STC files for both conditions in matlab, then do the difference and save the output in a new stc file that you can visualize with mne\_analyse. If you want to do statistics that's a bit more complicated. hope this helps Alex ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [March 17, 2011, 7:56pm UTC](https://mne.discourse.group/t/a-question-which-is-about-how-to-minus-two-conditions-in-freesurfer/288/3 "2011-03-17T19:56:44Z")
Hi,   mne\_average\_estimates (which is documented in the manual) should also be useful for algebraic manipulations on a set of stc files. Regards, Hari ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\ **Post date:** [July 13, 2011, 9:11am UTC](https://mne.discourse.group/t/a-question-which-is-about-how-to-minus-two-conditions-in-freesurfer/288/4 "2011-07-13T09:11:11Z")
Hi, I am so sorry to bother you again , I got some question these days > From (Dale et al., 2000).qi(t) is F distributed, with three degrees of freedom for the numerator. The degrees of freedom for the denominator is typically large, again depending on the number of time samples used to calculate the noise covariance matrix C. 1. in my study , my baseline is 100 ms , so I set F(0.95,3,100)=2.69 to be my fthresh of dSPM (x=2.69) ,is that right ? 2. I read out my stc file in MATLAB , and subtracted two condition ,then wrote back to stc file      should i use the same fthresh to show the result ? or don;t need to set any fthresh because I got some problem, if I used the same fthresh, after subtracting two condition, i didn;t see anything on dSPM I am so sorry to bother u again , hope anyone can help me   Eddie > Subject: Re: [Mne\_analysis] A question which is about how to minus two conditions in freesurfer > From: hari at nmr.mgh.harvard.edu > To: gramfort at nmr.mgh.harvard.edu > CC: e7362 at hotmail.com; mne\_analysis at nmr.mgh.harvard.edu > Date: Thu, 17 Mar 2011 15:56:44 -0400 > > Hi, >   mne\_average\_estimates (which is documented in the manual) should also > be useful for algebraic manipulations on a set of stc files. > > Regards, > Hari > \> Hi, > \> > \> \> these days , i use freesurfer and mne to analyze my MEG data > \> \> but now , i have a problem as follow : > \> \> 1.how can I minus two conditions , cus I wanna see the difference between > \> \> two conditions? EX: (deviant condition - standard condition) > \> > \> what is your setup? you want to compare within one subject? in a group > \> of subjects? > \> > \> if it's just one subject, an easy solution consists in loading the STC > \> files for > \> both conditions in matlab, then do the difference and save the output > \> in a new stc file that you can visualize with mne\_analyse. If you want to do > \> statistics that's a bit more complicated. > \> > \> hope this helps > \> > \> Alex > > The information in this e-mail is intended only for the person to whom it is > addressed. If you believe this e-mail was sent to you in error and the e-mail > contains patient information, please contact the Partners Compliance HelpLine at > [http://www.partners.org/complianceline](http://www.partners.org/complianceline) . If the e-mail was sent to you in error > but does not contain patient information, please contact the sender and properly > dispose of the e-mail. -------------- next part -------------- An HTML attachment was scrubbed... URL: [http://mail.nmr.mgh.harvard.edu/pipermail/mne\_analysis/attachments/20110713/0451d984/attachment.html](http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20110713/0451d984/attachment.html)