P-value of expected/observed proportion
Statistics question (I formalise a real biological question to explain it easier):
There is an urne with 1000 balls - 600 white and 400 black. You randomly pick up 100 balls, and observe 40 white and 60 black ones.
How to calculate the p-value of whether or not the observed proportion is significantly different from the random expecation?
Would a simple chi-square test do?
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grant.hovhannisyan
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ehm. I think there is something wrong with this formulation. You have an urn with 600/400 white/black balls and randomly picked up 100 balls. Your selected sample by definition is under null hypothesis (you took it from your initial urn). Why would you care about the p-value here?
Hi German, I want to see if there is a bias/selection towards picking-up, for example, white balls. BTW, congrats :)
Vielen Dank =) oh, so then it was not randomly selected? Use hypergeometric pdf https://en.m.wikipedia.org/wiki/Hypergeometric_distribution
De nada :) and thanks reaching!
This isn't a bioinformatics question, so you'll get better/more responses over at Cross Validated.
Doubt there will be better responses than mine!
There most definitely will be - it's the statistics SE.
You are actually right, I changed my answer to correct one