1. Calculate the sample size for each strata คำนวณกลุ่มตัวอย่างในแต่ละภูมิภาค/ชั้น
2. Separate population data into strta. The following steps will have to be applied for each strata
3. List the primary sampling units and their population sizes. Each cluster has its own Cluster population size
4. Calculate the cummulative sum of the population size
5. Determine the Number of Clusters that will be sampled in each strata
6. Determine the Number of Individuals to be sampled from each cluster. In order to ensure that all individuals in the population have the same number of individuals has to be sampled from each cluster
7. Divide the total population by the number of clusters to be sampled, to get the Sampling Interval (SI) with the confidence interval of 95%