We are working on a BOLD fMRI study with a visual stimulation block design. Participants get to see 4 visual stimuli categories in blocks.
Each participant belongs to one out of three "experimental" groups.
The variable of interest/DV is the peik height of the hemodynamic response measured by fMRI.
This peik height value for every subject is acquired for a range of brain structures.
Therefore I assume the following RM-ANOVA design:
- Dependent variable: peik height
- between subjects: group (3 levels)
- within subjects/repeated factors: stimulus (4 stimuli), brainstructure (regions of interest selected by literature)
There are no missing values. Data is organized in wide format.
- Can I use an RM-ANOVA design with two repeated factors in my case?
- How many levels may a repeated factor have? Is there a limit based on sample size or something else?
- Since there is no specialised post-hoc for RM-factors: may I use the ordinary paired t-test?