SPM Stats
You can test the significance of components by doing a one sample t-test or two
sample t-test on individual subject component images. We now provide an option in GIFT to do one sample
t-test or two sample t-test on images using SPM5.
- One sample t-test - One sample t-test for each component will be automatically
calculated if you set variable SPM_STATS_WRITE_TAL in
'icatb_defaults.m' to 1 or 2. If you set variable
"SPM_STATS_WRITE_TAL" value to 1 only one sample t-test will be
calculated whereas a value of 2 will also write talairach tables for the
t-map.
- Note: An option is also provided in
Utilities drop down box to calculate t-maps for the selected
data-sets.
- Two sample t-test - When you click
Utilities drop down box and have selected SPM Stats as the option, a
figure window will open to select the design criteria. When you select design as
"Two sample t-test", two sample t-test for a component will be calculated
between the selected groups by using a explicit mask. The explicit mask is
calculated by applying a threshold (SPM_STATS_TTEST_THRESHOLD) on t-map
obtained by doing a one sample t-test on data-sets.
- Note:
When you set SPM_STATS_TTEST2_EXPLICIT_MASK variable in
'icatb_defaults.m' file to 0, explicit mask is not used.