You are reviewing a scientific study where the epidemiologists sampled 1000 people from Charleston, South Carolina and measured variation at two loci, A and B. The haplotype frequencies in the sample population are:
AB = 0.406
Ab = 0.214
aB = 0.214
ab = 0.166
Toward the end of the article you are reviewing, you read that the 1000 people sampled were actually 600 non-hispanic whites [p(A)=.5, p(B) = .5] and 400 african americans [p(A) = 0.8 and p(B) = 0.8]. Assuming linkage equilibrium within each ethnic group, you check to see if the haplotype frequencies (and thus linkage disequilibrium) found in the overall sample of 1000 is really a function of population stratification. What do you conclude? p="the probability."
The soluton to this problem shows how the frequencies of the overall sample is a function of the population stratification.