Texas Instruments TI-84 Plus - 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.
S
Sx
1
2
n
1
-----------
Sx
2
2
n
2
-----------+=
df
Sx
1
2
n
1
-----------
Sx
2
2
n
2
-----------+
⎝⎠
⎜⎟
⎛⎞
2
1
n
1
1–
--------------
Sx
1
2
n
1
-----------
⎝⎠
⎜⎟
⎛⎞
2
1
n
2
1–
--------------
Sx
2
2
n
2
-----------
⎝⎠
⎜⎟
⎛⎞
2
+
----------------------------------------------------------------------------=
Sx
p
n
1
1–()Sx
1
2
n
2
1–()Sx
2
2
+
df
--------------------------------------------------------------------=
S
1
n
1
-----
1
n
2
-----
Sx
p
+=
df n
1
n
2
2–+=