STA 2023Testing the Difference Between Means (Small Independent Samples)

The Two-Sample t-Test for the Difference Between Means

Using the calculator

On the calculator: Press STAT, TESTS, and 4:2-SampTTest Since we have the sample statistics, choose stats

and fill in the information. Then select your alternate hypothesis. Then select No to pooled if your variances are not

equal or Yes if your variances are equal Last, select Calculate.

Output:

P-Value = .9971. This is greater that .05

Answer: At level of significance of 5% there is not enough evidence to reject the claim that the first population mean is less than or equal to the second population mean.

Using Data Using the raw data for a t-Test is more easy than

the z-Test. We just have to input the data and run the test

in the calculator. We do not need the standard deviations.

Example 2: Look at #19 on page 448. Output:

Answer: There is not enough evidence at the 1% level of significance to support the claim that the new treatment makes a difference in the tensile strength of steel bars.