Compare two proportions (Chi-square)

[h,p, chi2stat,df] = prop_test(X , N, correct)
A simple Chi-square test to compare two proportions
It is a 2 sided test with alpha=0.05

Input:

* X = vector with number of success for each sample (e.g. [20 22])
* N = vector of total counts for each sample (e.g. [48 29])
* correct = true/false : Yates continuity correction for small samples?

Output:

* h = hypothesis (H1/H0)
* p = p value
* chi2stat= Chi-square value
* df = degrees of freedom (always equal to 1: 2 samples)

Needs chi2cdf from the Statistics toolbox
Inspired by prop.test() in "R" but much more basic

Example: [h,p,chi]=prop_test([20 22],[48 29], true)
The above example tests if 20/48 differs from 22/29 using Yate's correction