Can the Fisher's exact test be used on anything bigger than a 2 X 2 table? For instance a 4 X 5
table? If yes can you direct me to a resource that demonstrates how to calculate this on excel?
Solution
The only problem with applying Fisher's exact test to tables larger than 2x2 is that the
calculations become much more difficult to do. The 2x2 version is the only one which is even
feasible by hand, and so I doubt that Fisher ever imagined the test in larger tables because the
computations would have been beyond anything he would have envisaged.
Nevertheless, the test can be applied to any mxn table and some software including Stata and
SPSS provide the facility. Even so, the calculation is often approximated using a Monte Carlo
approach.
Yes, if the expected cell counts are small, it is better to use an exact test as the chi-squared test is
no longer a good approximation in such cases.