Texas Instruments TI-83 - Page 409

Tables and Reference Information A-53
8399APXA.DOC TI-83 international English Bob Fedorisko Revised: 02/19/01 1:25 PM Printed: 02/19/01 1:40 PM
Page 53 of 58
The following is the definition for the 2
.
SampTTest. The
two-sample
t
statistic with degrees of freedom
df
is:
t
xx
S
=
−
12
where the computation of
S
and
df
are dependent on
whether the variances are pooled. If the variances are not
pooled:
S
Sx
n
Sx
n
=+
1
2
1
2
2
2
df
Sx
n
Sx
n
n
Sx
nn
Sx
n
=
+






−






+
−






1
2
1
2
2
2
2
1
1
2
1
2
2
2
2
2
2
1
1
1
1
otherwise:
Sx
nSxnSx
df
p
=
−+−() ()
11
2
22
2
11
S
nn
Sx
p
=+
11
12
df n n
=+−
12
2
and
Sxp
is the pooled variance.
2-SampTTest