If things are significant at .001, then there is probably an interaction, but you should also do a correction for multiple comparisons.
doug On 05/19/2012 09:55 PM, ZhiLiangLong wrote: > Hi Doug: > Thank so much for your suggestions. Please find Freesufer Digest, Vol > 99, Issue 23, Topic 11: > Question about DODS model and DOSS model. As you suggested, I have > four regressors: Group1 > Intercept, G2 Intercept, G1 slope, G2 slope, and the contrast [0 0 1 > -1].I will test the > interactions between group and age. Is that to say to test the null > hypothesis that G1 slope is > equal with G2 slope? > In qdec, while the analysis was complete, I cliked the Display tab and > saw a list of > questions summarizing the various analyses that were completed. And i > cliked on 'Does the > thickness--age correlation differ between Male and Female?' to test > whether there is no > interactions, and the qdec displayed the statistically significant > regions. I set threshold to > 0.001 and found all regions showing decreased thickness-age > correlation in Male relative to > Female(no increased thickness-age correlation was found). So, may i > draw the conclusion that > there is no interactions between group and age? However, if i set the > threshold lower (e.g. > 0.01), both increased and decreased thickness-age correlation was > found, does that mean the > interactions exist? if so, how do i set the threshold? > Hope you can give me some suggestions. > > -- 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: www.nmr.mgh.harvard.edu/facility/filedrop/index.html _______________________________________________ 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.
