Question

Sampling technique: Pick a sampling technique discussed in the textbook-Business Statistics. In your own language, explain the process of applying this method, in what situation it can be used, and its strengths/weaknesses. Give an example of where you can use this method in your work of life: specify the population, sampling technique, and sample.

Answer 1

Stratified random Sampling:

In this sampling technique, the elements of the population are divided into small sub-groups called strata based on the similarity so that the elements within the sub-group are homogeneous and the elements among different sub-groups formed are heterogeneous. And then the elements are randomly selected from each of these strata either proportionately or disproportionately. So, one needs to have prior information about the population regarding the attributes or characteristics in order to create sub-groups.

This sampling technique is used when we want to represent the population in its entirety with all different characteristics.

For example, in a school of boys and girls with different classes, if we need a sample, we divide it into strata of classes and also boys and girls in each class and then randomly pick the samples from each strata. Here, the population is all students of the school. Sampling technique is stratified random sampling. Sample is all the students who are randomly selected from each strata.

The strength of this sampling technique is that it better represents the population than the simple random sample. It enables us to compare the statistics among these different characteristics such as comparing mean marks of girls with that of boys and further testing of significance and deciding which sub-group of the population (boys or girls) contributed more to the overall marks of the school in a certain competition among schools. It is especially used when population is composed of different characteristics.