I want to compare two percentages to see how much they differ one from another. For example: I have 1000 products - 100 of them are on promotion. (10% products on promotion) The total products are divided into 3 subsets:
- Small products, (500)
- Medium products, (300)
- Large products. (200)
If I want to look at the large products (200) and 50 of them are on promotion at the moment. This gives us 25% of the Large products are on promotion at the moment.
What I want to do is to compare this two % in a way to show me how much they differ one from another. I don't think to subtract one from the another is a good way of doing this. I was looking at different statistical tests but I was not sure what I should use. How should I approach this (I will compare all subsets to the total individually)?
Thank you very much!