# How to test if a value is over-represented in one sample vs another

I have two multinomial data samples that both have N discrete categories. I know that a Kolmogorov-Smirnov test will let me know if the distributions of the two samples are different. But how can I statistically test if a particular category is significantly over-represented in one sample compared to the other?

• Is the category identified before looking at the data? Or do you mean 'in any category'? – Glen_b Mar 20 '14 at 2:54

If you're looking for this for a specific individual category then the test simplifies down quite a bit. You can think of the data as being binary where 1=in that cateogry and 0=not in that category. Then the number in that category for each sample will be a binomial distribution with parameter $p$ and your test is a simple hypothesis test that $p$ is equal for both samples.