 Here is the sample size calculation for difference in two proportionate percentage between two groups. Suppose you want to calculate the difference in proportion of anemia among lung cancer and bladder cancer patients. The formula is this. We need to substitute Z1 minus alpha whole square. Z beta we are not considering. There is a separate formula if we consider Z beta. P1 is the proportion in the first group and P2 is the proportion in the second group. Q1 is 100 minus P1, Q2 is 100 minus P2. D is the allowable error. Suppose lung cancer and bladder cancer patients have 40% and 60% prevalence of anemia. And then we will calculate Q1 and Q2 based on this. Precision is assumed as 4%. Then if we substitute the values, we will get 1052 in each arm.