Suppose in a complex survey with H strata and th selected PSUs in stratum h for h = 1,...,H, a total of nhα individual records are sampled from the αth PSU for α = 1,...th in the hth stratum. Therefore, the total sample size is
$$n={\sum}_{h=1}^H{\sum}_{\alpha=1}^{t_{h}}n_{h\alpha}.$$
Assume there are \(J\) mutually exclusive social groups in the population with \(J\geq2\). Let pj be the population share in group j and μj be the average health status in group j for j = 1,...,J.
Let yhαi be the health status for individual i in the αth PSU in the hth stratum, whαi be the survey weight value for individual i in the αth PSU in the hth stratum and \(\delta_{h{\alpha}i}^{j}{\in}(0,1)\) be the membership indicator (=1 if individual-hαi belongs to group j; 0 otherwise).