A paired-sample
t test
compares the mean of the differences in the observations to a given
number, the null hypothesis difference. The paired-sample
t test
is used when the two samples are correlated, such as two measures
of blood pressure from the same person.
To compare
n paired
differences to a value
m, use
![t equals . fraction d with macron above , minus m , over fraction s sub d , over square root of n end fraction end fraction](images/t_test_paired_sample.png)
, where
![d with macron above](images/d_bar.png)
is the sample mean of the paired differences and
s2d is
the sample variance of the paired differences.