Texas Instruments TI-84 - page 637

Appendix B: Reference Information 634
where the computation of S and df are dependent on whether the variances are pooled. If
the variances are not pooled:
otherwise:
and Sxp is the pooled variance.
SSx12
n1
-----------Sx22
n2
-----------+=
df
Sx12
n1
-----------Sx22
n2
-----------+
⎝⎠
⎜⎟
⎛⎞
2
1
n11–
-------------- Sx12
n1
-----------
⎝⎠
⎜⎟
⎛⎞
21
n21–
-------------- Sx22
n2
-----------
⎝⎠
⎜⎟
⎛⎞
2
+
----------------------------------------------------------------------------=
Sxp
n11–()Sx12n21–()Sx22 +
df
--------------------------------------------------------------------=
S1
n1
----- 1
n2
-----Sxp
+=
df n1n22–+=