-7-
Unpaired
2 Sample t-Test: Cartoon Data
Signal
in
Voxel,
in
each
condition,
from
7
subjects
(% change)
Condition
#
1
Condition
#
2
±1 SEM
-2 SEM
+2 SEM
¥ Condition = some way to categorize data (e.g., stimulus type, drug treatment, day of scanning, subject type, É)
¥ SEM = Standard Error of the Mean = standard deviation of sample divided by square root of number of
samples
= estimate of uncertainty in sample
mean
¥ Unpaired t-test determines if sample means are Òfar apartÓ compared to size of SEM
¥ t statistic is difference of means divided by SEM
one data
sample
=
signal
from
one
subject
in this
voxel
in
this
condition
¥ Not significantly different!