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help > RE: repeated measures ANOVA + covariate
Mar 22, 2023 02:03 AM | Andrew Zalesky
RE: repeated measures ANOVA + covariate
PS.
I should say that my remarks are not specific to the NBS. This is a general property of the general linear model (GLM).
Originally posted by Andrew Zalesky:
I should say that my remarks are not specific to the NBS. This is a general property of the general linear model (GLM).
Originally posted by Andrew Zalesky:
Hi
Maksym,
Because the main effect of group does not change between the two time points, a within-subject design (i.e. two time points) is not needed to assess the effect of group.
If you are specifically interested in the main effect of group, you could consider only the data from the first time point (or only the data for the second time point). No need to collect follow-up data if group is the only effect of interest.
Alternatively, you could first compute the difference in the neuroimaging measure between the two time points for each subject and then run the NBS on the difference. This means that each subject would only have one measurement in the design matrix, which would be the difference between the two time points.
With these two alternatives, the effect of age can be modelled by including a column with age in the design matrix. The interaction between age and group could also be tested. Both alternatives will require you to create a new design matrix.
Andrew
Originally posted by Maksym Tokariev:
Because the main effect of group does not change between the two time points, a within-subject design (i.e. two time points) is not needed to assess the effect of group.
If you are specifically interested in the main effect of group, you could consider only the data from the first time point (or only the data for the second time point). No need to collect follow-up data if group is the only effect of interest.
Alternatively, you could first compute the difference in the neuroimaging measure between the two time points for each subject and then run the NBS on the difference. This means that each subject would only have one measurement in the design matrix, which would be the difference between the two time points.
With these two alternatives, the effect of age can be modelled by including a column with age in the design matrix. The interaction between age and group could also be tested. Both alternatives will require you to create a new design matrix.
Andrew
Originally posted by Maksym Tokariev:
Thank you for the detailed answer. If I
understand correctly, it is not possible to test directly the main
effect of group with repeated measures 2x2 design. As such, I have
another question. What is the approach to test the main effect of
group with two groups, two sessions while accounting for the age
variability? Does one have to construct a separate design? These
questions might be straightforward, however, some explanation would
be helpful.
Thank you again for helping with the design and NBS.
Best regards,
Maksym
Thank you again for helping with the design and NBS.
Best regards,
Maksym
Threaded View
| Title | Author | Date |
|---|---|---|
| Maksym Tokariev | Mar 21, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |
| Maksym Tokariev | Mar 22, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |
| Maksym Tokariev | Apr 17, 2023 | |
| Andrew Zalesky | Apr 18, 2023 | |
| Andrew Zalesky | Mar 22, 2023 | |