That looks right. You can use 1/6 instead of 1/3, but that will not make a difference in the final p-values
On 05/24/2017 11:00 AM, Worker, Amanda wrote: > > Hi all, > > > I have a repeated measures design with two groups (drug and placebo) > and two time points (baseline and follow-up). The groups are not very > well matched so I'd like to control for age and gender. The data was > also acquired across three sites which I'll need to control for. I do > not have any drop outs. > > > Essentially, I want to know if there is a significant effect of drug > on cortical thickness. > > > I've tried this out in qdec, but because I have site (with three > levels) qdec isn't appropriate, so I'm trying to set up my own fsgd > and contrast matrix. Because I have already created the percent change > and symmetrized percent change files (as part of qdec prep) I thought > I might be able to simply run a t-test on those. Which would answer > the question...'is there a significant difference in percent change > for the drug and placebo groups'. Does this seem like a sensible approach? > > > If the above does seem sensible, I am not quite sure how to set up my > contrast matrix. As I have three categorical variables to include > (Treatment, Gender, Site) and only one continuous variable (age). This > would leave me with 12 classes (DrugFemaleSite1, DrugMaleSite1, > DrugFemaleSite2, DrugMaleSite2 etc etc) and one variable. > > > Would it look something like this? Or is this absurd? > > > 0.333 0.333 0.333 0.333 0.333 0.333 -0.333 -0.333 -0.333 -0.333 -0.333 > -0.333 0 0 0 0 0 0 0 0 0 0 0 0 > > > Thanks in advance, > > > Amanda > > > > > _______________________________________________ > Freesurfer mailing list > Freesurfer@nmr.mgh.harvard.edu > https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer -- Douglas N. Greve, Ph.D. MGH-NMR Center gr...@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422 Bugs: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting FileDrop: https://gate.nmr.mgh.harvard.edu/filedrop2 www.nmr.mgh.harvard.edu/facility/filedrop/index.html Outgoing: ftp://surfer.nmr.mgh.harvard.edu/transfer/outgoing/flat/greve/ _______________________________________________ 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.
