¥Overview of Statistical Testing of Group Datasets with
AFNI programs
HParametric Tests:
åAssume data are normally distributed (Gaussian)
í3dttest (paired, unpaired)
í3dANOVA (or 3dANOVA2 or 3dANOVA3)
í3dRegAna (regression, unbalanced
ANOVA, ANCOVA)
í3dANOVA4 = Matlab script for one-,
two-, three- and four-way ANOVA
HNon-parametric analyses:
åNo assumption of normality
åTends to be less sensitive to outliers (more robust)
í3dWilcoxon (~t-test
paired)
í3dMannWhitney (~t-test
unpaired)
í3dKruskalWallis (~3dANOVA)
í3dFriedman (~3dANOVA2)
íPermutation
test
åLess sensitive and less flexible than parametric tests
åIn practice, seems to make little difference
íProbably
because number of datasets and subjects is usually small (hard to tell if data is non-Gaussian
when only have a few sample points)