=+12. A population of items is partitioned into k strata of sizes N1, N2, . . . , Nk. Using proportional allocation, random samples of size n1, n2, n3, . . . , nk are selected from the strata and the numbers x1, x2, x3, . . . , xk of items having a specified characteristic are determined. Sample proportions p1, p2, p3, . . . , pk are then computed (i.e., pi 5 xi