Stop sending me this shit > Wiadomość napisana przez Kai Ohmstedt <kai.ohmst...@googlemail.com> w dniu > 13.03.2018, o godz. 02:02: > > Hi Douglas, > > thank you for the explanation of the contrasts, this helped a lot! > > > All the best, > > Kai > > 2018-03-12 18:20 GMT+01:00 Douglas N. Greve <dgr...@mgh.harvard.edu>: >> Yes, let's say you have 4 groups (eg, gender and sequence) and one covariate >> (BDI score). If you use a DODS model, then you will have 8 regressors (4 >> intercepts and 4 slopes). To test for an effect of covariate regressing out >> the group, then you would have >> >> [0 0 0 0 .25 .25 .25 .25] >> >> The +0.25 computes the mean slope across all groups (note you could also >> just use all 1s, you will get the same p-value). >> >> >> >>> On 03/09/2018 01:43 PM, k.ohmst...@stud.uni-heidelberg.de wrote: >>> Hi Douglas, >>> >>> thanks for the advice. >>> >>> I have one more question: I want to find correlations of the lGI and the >>> respective psychometric measurement, regressing out the effect of gender, >>> sequence and the other covariates. >>> I just had a look at the examples of FSGDs containing two factors with two >>> levels each and as far as I understand it, it is only possible to compare >>> two of the groups or to find an interaction between groups and covariates. >>> >>> Is it at all possible to find out how the lGI is correlated to one of my >>> covariates, i.e. higher values of Beck's Depression Inventory correlate >>> with higher/lower values of the lGI, when regressing out the other factors? >>> If yes, how do I build the contrast file to do so correctly? I am stuck >>> here. >>> >>> Thank you for the time and effort! >>> >>> >>> Best regards >>> >>> Kai >>> >>> Zitat von Douglas Greve <dgr...@mgh.harvard.edu>: >>> >>>> Hi Kai, please remember to post to the list. Your FSGD file is not >>>> quite right. Gender is a discrete variable and should be represented by >>>> two groups not as a covariate. If Sequence is discrete, then you need >>>> four groups (Gender by Sequence). >>>> >>>> doug >>>> >>>> >>>>> On 3/9/18 3:20 AM, k.ohmst...@stud.uni-heidelberg.de wrote: >>>>> Dear Douglas, >>>>> >>>>> the fsgd file I used is attached. Thank you for your help! >>>>> >>>>> >>>>> Best regards >>>>> >>>>> Kai >>>>> >>>>> Zitat von "Douglas N. Greve" <dgr...@mgh.harvard.edu>: >>>>> >>>>>> can you send your fsgd file so that I have a better idea of what you are >>>>>> mentioning? >>>>>> >>>>>> >>>>>>> On 03/08/2018 08:39 AM, k.ohmst...@stud.uni-heidelberg.de wrote: >>>>>>> Dear all, >>>>>>> >>>>>>> I am trying to correlate psychometric measurements and the local >>>>>>> Gyrification Index. >>>>>>> To do so, I use the FreeSurfer pipeline to calculate the lGI and then >>>>>>> PALM, following the advice in this thread >>>>>>> (https://mail.nmr.mgh.harvard.edu/pipermail//freesurfer/2017-March/050703.html). >>>>>>> All my subjects are part of the same group, so I used a FSGD with the >>>>>>> group "main" to create the design matrix and mask for my data that are >>>>>>> required by PALM. >>>>>>> Having a closer look at the design matrix that was created, I found >>>>>>> that there was a variable for the group that was the same for all my >>>>>>> patients. As it is the same for all patients, I thought eliminating it >>>>>>> would not be a problem. But after re-running PALM without it, there >>>>>>> were huge differences in my results and effects were notably larger >>>>>>> and more significant. >>>>>>> >>>>>>> Do any of you have any experience which option is best in this case? >>>>>>> Is it a valid choice to eliminate the variable for the group, as it is >>>>>>> the same for each patient anyway? >>>>>>> >>>>>>> Furthermore, would you recommend centering for the design matrix? I >>>>>>> found that this can have an impact, but I am lost on in which cases it >>>>>>> should be done and in which it shouldn't. >>>>>>> >>>>>>> >>>>>>> Thank you for your help! >>>>>>> >>>>>>> >>>>>>> Best regards >>>>>>> >>>>>>> Kai Ohmstedt >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> Freesurfer mailing list >>>>>>> Freesurfer@nmr.mgh.harvard.edu >>>>>>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>>>>> >>>>>> _______________________________________________ >>>>>> Freesurfer mailing list >>>>>> Freesurfer@nmr.mgh.harvard.edu >>>>>> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer >>>>>> >>>>>> >>>>>> 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 . 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. >>>>>> >>>>>> >>>>> >>>>> >>> >>> >>> >> > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer > > > 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 . 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.
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