Fishers Exact Test In Excel Made Easy

Performing statistical tests can be a daunting task, especially for those without a strong statistical background. However, with the right tools and knowledge, it can be made much easier. In this article, we will focus on the Fisher Exact Test, a statistical test used to determine if there are non-random associations between two categorical variables. We will also explore how to perform this test in Excel, making it more accessible to a wider range of users.

The Fisher Exact Test is particularly useful when working with small sample sizes or when the data does not meet the assumptions of other statistical tests, such as the Chi-Square Test. It is commonly used in various fields, including medicine, social sciences, and marketing research.

What is the Fisher Exact Test?

The Fisher Exact Test is a statistical test used to determine if there are non-random associations between two categorical variables. It is based on the hypergeometric distribution and is used to calculate the probability of observing a particular distribution of data, or a more extreme distribution, assuming that there is no real association between the variables.

The test is called "exact" because it calculates the exact probability of observing the data, rather than relying on an approximation. This makes it a more accurate test, especially when working with small sample sizes.

When to Use the Fisher Exact Test

The Fisher Exact Test is commonly used in the following situations:

When working with small sample sizes
When the data does not meet the assumptions of other statistical tests, such as the Chi-Square Test
When the data is categorical and there are only two variables
When the researcher wants to determine if there is a non-random association between two variables

How to Perform the Fisher Exact Test in Excel

Performing the Fisher Exact Test in Excel is a relatively straightforward process. Here are the steps:

Prepare the data: Enter the data into a table in Excel, with the two categorical variables in separate columns.
Select the data: Select the data range, including the headers.
Go to the "Data" tab: Click on the "Data" tab in the ribbon.
Click on "Data Analysis": Click on the "Data Analysis" button in the "Analysis" group.
Select the "F-Test Two-Sample for Variances" option: Select the "F-Test Two-Sample for Variances" option from the list of available tests.
Click "OK": Click "OK" to run the test.

Steps to Perform Fisher Exact Test in Excel

The output will include the test statistic, the p-value, and the degrees of freedom.

Interpreting the Results

The results of the Fisher Exact Test are interpreted as follows:

p-value: The p-value represents the probability of observing the data, or a more extreme distribution, assuming that there is no real association between the variables. If the p-value is less than 0.05, it is generally considered to be statistically significant.
Test statistic: The test statistic represents the number of observations in each category. If the test statistic is significant, it indicates that there is a non-random association between the variables.

Example of the Fisher Exact Test in Excel

Suppose we want to determine if there is a non-random association between the color of a person's eyes and their hair color. We collect data from a sample of 100 people and enter it into an Excel table.

We follow the steps outlined above and run the Fisher Exact Test. The output includes a p-value of 0.01, which is less than 0.05. This indicates that there is a statistically significant association between the color of a person's eyes and their hair color.

Conclusion

The Fisher Exact Test is a useful statistical test for determining if there are non-random associations between two categorical variables. It is particularly useful when working with small sample sizes or when the data does not meet the assumptions of other statistical tests. By following the steps outlined in this article, you can easily perform the Fisher Exact Test in Excel and interpret the results.