First of all, researcher identifies the target population out of the whole population. Target population is the population of interest in which researcher wants to infer his/her findings of the study. Accessible population is the part of target population which the researcher can reach out to investigate. After finding out the accessible population, sampling frame is made to draw out the sample out of it. Sampling frame is nothing but the list of all elements/units in a population from which sample will be taken out. Frame helps to identify everyone in the population so that everyone can get equal chance of selection for the study. Sample is the unit(s) where the researcher does his investigation.

Stages involved in the selection of sample from a target population is described below:

PROCESS IN DETAIL:

1. Identify the Target population (Population of interest)

Target population refers to the group of individuals or objects to which researchers are interested in generalizing their findings. The target population is the group of individuals or objects, from which the sample might be taken. A well - defined population reduces the probability of including the participants who all are not suitable for the research objective.

For example, researcher wants to study the behaviour of toddlers in playgroup. He has to select a particular area (e.g., all playgroups in his city) for his study because it is impossible to study the whole world toddlers.

2. Select a sampling frame

While selecting sample units from the population, it is sometimes desirable to choose a list of the population from which the researcher select units. Sampling frame is the group of individuals or objects (e.g., list of all playgroups in researcherâ€™s city) from which researcher will draw his/her sample. It is the list of all units in a study population from which the sample is taken.

For example, researcher takes 3 playgroups near to his house in his sampling frame to conduct his study.

3. Specify the sampling technique

Sampling can be done through probability (random selection) or non-probability (non-random) technique. Now, if the sampling frame is approximately the same as the target population, random selection may be used to select sample. On the other hand, if the sampling frame does not really represent the target population, the researcher may choose non-random selection which can give at least an idea about the population in his nearby area.

4. Determine the sample size

The sample size is simply the number of units in the sample. Sample size determination depends on many factors such as time, cost, facility. In general, larger samples are better, but they also require more resources.

5. Execute the sampling plan

Once population, sampling frame, sampling technique and sample size are identified, researcher can use all that information to choose his/her sample.