it's link to learn chisquare test http://www.socscistatistics.com/tests/chisquare/

Hi Umar,

If there is homogeneity, you can just add them up. since there is a confounding variable, traditional method will definitely lose some information if you just add all the k contingency tables together to make a 2 by 2 table.

i recommend Mantel-Haenszel method.

 μk = E(n11k) = n1+kn+1k/n++k

νk^2=Var(n11k) = n1+k*n2+k*n+1k*n+2k/[n++k^2(n++k −1)]

the statistic is [sum_k_(n11k)-sum_k_(μk)]^2/sum_k(νk^2)

hope this will help you.

What you want to find out is not clear. Could you be more explicit?