Inferences about Two Populations
Two Sample Z-Interval

Consider the results shown below for independent random samples taken from two populations :

Give the point estimate of the difference, and provide a 95% confidence interval for the difference between the means.

We will start from the "TESTS" menu . Press (see screen below)

Arrow right to "TESTS" and down to choice "9 : 2 SampZInt..."
Press (you will see this screen)

Once again you must choose "Data" or "Stats". We will choose "Stats". [Recall we are entering s1, s2 for 1, 2.]

Change your settings to match the settings on these screens:

Arrow down and highlight "Calculate" ( you will see this screen)

Press (this screen will appear)

As you can see from the screen the 95% confidence interval for the difference of the means is (.83396 , 3.166 )

The point estimate can also be calculated from this screen .

It is 13.6 11.6 = 2.0 .