11-14 Inference aplet
Two-Sample T-Test
Menu name T-Test: μ1 – μ2
The Two-sample T-Test is used when the population 
standard deviation is not known. On the basis of statistics 
from two samples, each sample from a different 
population, this test measures the strength of the evidence 
for a selected hypothesis against the null hypothesis. The 
null hypothesis is that the two populations means are 
equal H
0
: μ
1 
= μ
2
.
You select one of the following alternative hypotheses 
against which to test the null hypothesis
Inputs The inputs are:
H
1
:μ
1
μ
2
<
H
1
:μ
1
μ
2
>
H
1
:μ
1
μ
2
≠
Field 
name
Definition
Sample 1 mean.
Sample 2 mean.
S1 Sample 1 standard deviation.
S2 Sample 2 standard deviation.
n1 Sample 1 size.
n2 Sample 2 size.
α Significance level.
_Pooled? Check this option to pool samples 
based on their standard deviations.
x1
x2
HP 39gs English.book  Page 14  Wednesday, December 7, 2005  11:24 PM