Question

Describe some sampling situations in which a sampler which takes a stratified sample would be necessary.

Answer 1

Examples of stratified sampling requirements-

1. Suppose, we are interested to compute monthly salary of all staffs of a company. Now a company consists of staffs of different designations whose salaries differ significantly. In order to perform quality statistical analysis we have do divide all staffs into smaller homogeneous strata. Here strata may be divided as managing members, office bearers, permanent labors, contractual labors and other non-production workers (including security guards, electrician, cleaning staffs).
2. Suppose, we are interested to analysis time spent by people of a locality in exercise. If we merely perform statistical sampling then it will make a mess. We have to divide people into different homogeneous strata. Here strata may be divided as child, teenagers, youth, mid-age persons and retired persons (above 60). Another way of stratification may be based on health condition as healthy people and people surviving in long term diseases.
3. While we wish to access economical situation and problems arose among people of a country due to sudden outbreak of COVID-19, we can not merely collect data about all types of people together. We have to divide people in different homogeneous strata as government employees, non-government job holders, businessmen, daily labors, shop-keepers and farmers.
4. Suppose, we are interested to estimate prevalence of COVID-19 among people. In such situation we cannot merely collect data all over the world. We have to divide places upon climate and weather. Further more important is to make strata of people of same region depending upon age and sufferings of undergoing health issues.