Texas Instruments TI-83 PLUS - Manual (Page 729)

TI-83 Plus Tables and Reference Information 726
2 . SampTTest
The following is the definition for the 2 . SampTTest. The two-sample t
statistic with degrees of freedom df is:
S
x x
t
2 1
−
=
where the computation of S and df are dependent on whether the
variances are pooled. If the variances are not pooled:
2
2
2
1
2
1
n
Sx
n
Sx
S
+ =
2
2
2
2
2
2
1
2
1
1
2
2
2
2
1
2
1
1
1
1
1






−
+ 





−






+
=
n
Sx
n n
Sx
n
n
Sx
n
Sx
df