**Statistical test to determine equality of variance**

Inorder to do a T-test it is must that two sample groups have equal variance. F-test is done to compare the variance in the two groups.

- Select Tools/ Data Analysis / F-Test Two Sample for Variance.

In the F-Test Two Sample for Variance dialog box: For the Input Range for Variable 1, highlight the nine values from $A$2:$A$10.

For the input range for Variable 2, highlight the seven values from $B$2:$B$10. Leave the other items at their default selections. This dialog box is shown below. Click OK.

**The following results are produced by Excel:**

A. If the variances are assumed to NOT be equal, proceed with the t-test that assumes non-equal variances.

B. If the variances are assumed to be equal, proceed with the t-test that assumes equal variances.

T-test

The t-test in Excel is similar for both the equal and unequal variances case – the main difference is which version you select from the menu. Assuming that you have selected the unequal version of the two-sample t-test – this is how you proceed.

Select Tools/ Data Analysis/ t-Test: Two Sample assuming equal Variances

For the Input Range for Variable 1, highlight the nine values from $A$2:$A$10. For the input range for Variable 2, highlight the nine values from $B$2:$B$10. Leave the other items at their default selections. This dialog box is shown below. Click OK.

The following output is created:

The two tailed calculated t-statistic is 0.875 and the highlighted p-value for this test is p=0.39 Since the p-value is more than 0.05, this provides evidence to accept the null hypothesis of equal means.

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