In: Psychology
8. Why choose stratified sampling? Mention two main reasons.
9. What is the difference between a “random” (probability) sample and a nonrandom sample?
A sample is any number of individuals taken from the population for the purpose of research analysis. A sample is considered to be the true representation of a population. There are different methods of collecting a sample. The two methods are; Probability Sampling and Non-Probability Sampling.
Probability Sampling is when every individual has equal, probable chances of being selected in the sample. Non-Probability Sampling on the other hand, provides no accurate basis of including individuals in a sample and them being the true representation of the population. The whole idea behind sampling is to extract a smaller amount of individuals from a worldwide population while still representing the population.
Stratified sampling method is a form of sampling wherein the researcher equally or proportionally divides the sample in different subgroups or strata. For instance, a researcher wants to study the effect of work pressure on depression. His total sample is 500. In a stratified sample he would randomly choose 500 people, however, divide them equally in two groups of 250 males and 250 females.
The advantages of stratified sampling are; it is the most accurate representation of the population within the strata or subgroups. The results of the study are more reliable and valid in comparison to other sampling methods.