Hi,
I'm a beginner of fsl and hope someone could help me to figure our this simple question......
http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FEAT/UserGuide#Group_Statistics
In the ANOVA 1-factor 4-levels session, the example in this guide explains:
"We have 8 subjects and 1 factor at 4 levels A, B, C and D. The first two inputs are subjects in condition A, the next two are B etc. To compare a level with another we could just have one EV per level. However, if we want to ask the ANOVA question - where is there any treatment effect then we can do the following. EV1 fits condition D (it is the only nonzero EV during condition D). EV2 fits A relative to this, i.e. represents A-D (see below for explanation). The F-test then tests for any deviation - ie any difference between the levels, and corresponds exactly to the standard ANOVA test."
My question is, why is the EV for Condition D not:
0
0
0
0
0
0
1
1
?
Also, in ANOVA, the test is significant if the difference of any combination of the 4 levels is different, isn't it? But the contrasts only contain A-D, B-D and C-D, without containing A-B, B-C, A-C....
Thanks for any clarification of my concept.
Mark
|