Need to Run a Fisher's Exact Test but Don't Know How?
QI Macros add-in can run a Fisher's Exact test for you right in Excel!
Fisher's Exact test using QI Macros:
- Select your data.
- Click on QI Macros menu > Statistical Tools > F & t Tests > Fisher's Exact Test.
- QI Macros will do the math and analysis for you.
What is a Fishers Exact Test of a 2x2 Table?
A Fisher Exact Test evaluates small, 2x2, tables better than Chi-Square because it calculates the exact probability. A Fishers Exact Test of a 2x2 table helps identify if there are differences between two or more demographics. Consider the following example.
Fisher Exact Test Example using QI Macros
Imagine asking men and women if they are dieting. How will we know if one sex diets more than the other? We can develop a null hypothesis (H0) that men and women diet equally and an alternate hypothesis (Ha) that they are different:
Now, conduct the survey and enter the number of responses into Excel. As you can see, men seem to diet less than the women do, but is it statistically different?
Select your data and click on QI Macros Menu > Statistical Tools > f and t Tests > Fishers Exact Test (2x2):
The Fisher Exact Test macro will calculate:
- exact test p value (.00276)
- chi-square p value (.00093)
Interpreting Fishers Exact Test results
- H0 men = women
- Ha men < > women
|p value < a||Reject the null hypothesis|
|p value > a||Cannot Reject the null hypothesis (Accept the null hypothesis)|
In the results above, the Fisher's Exact Test p value is 0.00276. We can reject the null hypothesis at the 0.05 and 0.01 levels, but not the 0.001 level of a.
Notice that the Fisher Exact test p value is higher than the chi-square p value of 0.00093. Chi-square would let us reject the null hypothesis at the 0.001 level.