F-Test in Excel

F-Test in Excel

An F-test is a statistical tool in hypothesis testing to test whether or not the variances of two populations are equal. This is often used to determine which kind of t-test to use when we want to test the equality of the means of two groups of data.

0:00 F-test introduction 0:52 Defining the Problem for the F-test 1:18 Performing the F-test in Excel 2:09 F-test Output - Variable information 2:41 P-values

We assume that the underlying distributions of the data sets are normal and the data sets are independent. When the variances of the data sets are equal we have to use another t-test than when the variances are unequal.

To test if the variances of two data sets are equal or not, we state our null hypothesis H_0 as the variance of the first population equals the variance of the second population. The alternative hypothesis is then the variance of the first population is not equal to the variance of the second population.

To perform the F-test, we navigate to Data and select Data Analysis. A menu opens where we scroll down to the F-test and select this. We press Ok and a menu opens where we have to enter some data for testing.

We did not include the labels in the variable ranges, so we keep this box unchecked. And we have to enter the level of confidence for our test. This is automatically set to 0.05 which corresponds to a 95% confidence level. This is a commonly used level, so we keep this. Finally, we choose where the output of the F-test should appear.

The output table appears on the screen. The first half of this table summarizes the variables. We see the means, variances, the number of observations, and the number of degrees of freedom. Next, we see the value of the test F-statistic, the p-value, and the critical F-value for a one-tailed test.

Here, the F-statistic is smaller than the critical F-value, so we can conclude that the variance of the first population is significantly different from that of the second population.

Another way to conclude this is by making use of the p-value. The p-value for the test is 0.0001. This value is smaller than our confidence level of 0.05, so we can conclude to reject the null hypothesis.

This concludes our tutorial on F-test in Excel. I'm inspired by content creators as Leila Gharani and Teacher's Tech.

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