Filter
Top Products
Example: Average Salaries
Test at the 1% significance level if the 2001 mean salaries of full-time state employees in New
York and Massachusetts are different.
We are testing to choose between H
0
: µ1 = µ2 and H
1
: µ1 ø µ2. Since we have the population
standard deviations, we will use 2-SampZTest.
Press the STAT key.
Press the ► key twice to highlight TESTS.
Press the number 3 key.
Move the cursor over Stats and press the ENTER key.
Type in 9000 for σ1
.
Type in 8500 for σ2.
Type in 49056 for Ë1.
Type in 500 for n1.
Type in 46800 for Ë2.
Type in 400 for n2.
Move the cursor over øµ2 and press the ENTER key.
Move the cursor over Calculate and press the ENTER key.
The 2-SampZTest output shows the:
alternative hypothesis: µ
1
ø µ
2
test statistic: Z=3.854158502
p-value: P=1.1617127E-4
sample means and sample sizes
The p-value is 1.16 × 10
−4
, which is less than 1%. We reject the null hypothesis and conclude
that the mean salaries do differ.
Paired Samples
The confidence intervals and hypothesis tests described above all assume that the samples are
taken independently. Two samples that are taken from the same population are said to be
dependent. The most common data collection design with dependent samples is called
63