Texas Instruments -84 Plus, Manual Book

Page: 637 / 696

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 – + =