 |
 |
Instead of estimating the within-subject slopes, I'd do a repeated measures ANOVA. In the ANOVA, you will want subject, group, time, and a group-by-time interaction term. The reason for doing it this way is to avoid the assumption that the change is linear with time. On Wed, Mar 18, 2009 at 10:01 PM, Kyle Kern <[log in to unmask]> wrote: > Hi, > I am trying to set up a longitudinal tbss analysis over 4 time points > contrasting a patient > group to a control group. I'm interested in change over time rather than > the effect of any > specifc time point. I was planning to model the slope for each subject and > then put this > into a group t-test. Would modelling the slope for each subject be the same > approach as a > simple correlation where my design matrix might look like this?: > > -3 > -1 > 1 > 3 > > Would this reflect the magnitude of the slope or does it only reflect the > linearity like a > correlation coefficient? I would hypothesize that patients show a steeper > slope than > controls though they may show more variability, so a least squares > regression slope > might detect differences but a simple correlation coefficient might not. > > Also, to perform a 2 level analysis with tbss is it preferable to use > randomise and feed > the within subject t-stat into the group comparison or should I use the > feat gui and treat > each within subject analysis as a timeseries and feed that into a higher > level mixed > effects analysis? > > thanks for all the help, > > Kyle Kern > -- Best Regards, Donald McLaren ===================== D.G. McLaren University of Wisconsin - Madison Neuroscience Training Program Office: (608) 265-9672 Lab: (608) 256-1901 ext 12914 ===================== This e-mail contains CONFIDENTIAL INFORMATION which may contain PROTECTED HEALTHCARE INFORMATION and may also be LEGALLY PRIVILEGED and which is intended only for the use of the individual or entity named above. If the reader of the e-mail is not the intended recipient or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that you are in possession of confidential and privileged information. Any unauthorized use, disclosure, copying or the taking of any action in reliance on the contents of this information is strictly prohibited and may be unlawful. If you have received this e-mail unintentionally, please immediately notify the sender via telephone at (608) 265-9672 or email.