¥ANOVA:
Which levels had an effect or were different from one another?
¥Usually, just knowing that there is a main effect (some of the means are different,
but no information about which ones) isnÕt enough, so there
is a number of
options to let you look for more detail
¥Which treatment means (mi )
are 0 ?
åe.g., is the response of subjects in level #3 different from 0 ?
åt-statistic
with option -mean in 3dANOVA
åSimilar to using 3dttest -base1 0 (single sample test) to test only the data from
those subjects
¥Which treatment means are different from each other ?
åe.g., is the response of subjects in level #3 different from those in level
#2 ?
åt-statistic
with option -diff in 3dANOVA
åSimilar to using 3dttest
(unpaired) between the data from these sets of subjects
¥Which linear combination of means (contrasts)
are 0 ?
åe.g., is the average response of subjects in level #1 different from the combined
average of subjects in levels #2 and #3 ?
åt-statistic
with option -contr in 3dANOVA
¥