¥1-Way ANOVA
HProgram 3dANOVA
åDetermine whether treatments (levels) of a single factor (independent
parameter)
has an effect on the measured response (dependent parameter, like FMRI percent
signal change due to some stimulus).
åExamples of factor: subject type, task type, task
difficulty, drug type, drug dosage, etc.
åWithin a factor are levels: different
sub-categorizations
íExample: factor=subject type; level 1=normals, level 2=patients
with mild symptoms, level 3=patients with severe symptoms
åThe various AFNI ANOVA programs differ in the number of factors
they allow:
3dANOVA allows 1 factor, comprising up to 100 levels
HAssumptions
åValues are normally distributed
åNo assumptions about relationship between dependent and
independent variables (e.g., not necessarily linear)
åIndependent variables are qualitative
HCan also use 3dttest
if there are only two levels
åThe 1-way 3dANOVA
analysis is a generalization to multiple levels of an unpaired 3dttest (for generalization of paired,
wait for 3dANOVA2)
HExample: r different types of subjects performed the same
task in the scanner