If you make an opinion poll over which party people will vote on in a country with seven partys, you get different percentages for the different partys, based on a sample. Say one party has, according to the poll, increased its voters from 5 to 10 percentage points. You want to test if this is statistical significant. What kind of distribution are you using then? It cannot be the normal, can it? Maybe the multinomial, as in septimonial? Or is it the binomial? Which one is it and why is it that one? Hope someone knows and can explain a little bit!