What is sampling? Explain various methods of sampling?

 Sampling Methods: As mentioned above, in sample enquiry, only a part of population is taken into account, which is assumed to be representing the whole population. The technique of selecting items for the sample is called sampling method. Sampling methods are broadly grouped as probability and non-probability methods.

Probability Sampling Methods

If the sample is obtained by the methods of selection, wherein each item of the population has an equal chance or same probability of being selected, then the method is referred as Probability Sampling Methods. Some of the Probability Sampling Methods are given below:

1. Simple Random Sampling: In this sampling method, chance alone is allowed to decide which items from the population are to be selected. Therefore, it is also called chance or lottery method. This is done by numbering randomly of all the items of the population. This method is employed for homogeneous population.

2. Systematic Sampling: This is a systematic way of random selection. In this technique, items taken for sample are arranged in some serial order and then every nth item from the list is selected until the desired number is secured.

3. Stratified Sampling: Stratified sampling is used for non-homogeneous groups. Under this method, population is classified into different homogeneous groups on the basis of certain proportion or any characteristic. These homogeneous groups are known as strata. After stratification, the sample items are randomly selected from each stratum.

4. Cluster Sampling: In this technique, the population is classified into heterogeneous groups called clusters and then few such clusters are selected at the random basis for enquiry.

5. Area Sampling: Under this method, a large geographical area under consideration is divided into smaller units and then desired numbers of these units are selected randomly for investigation purpose. This method is quiet similar to cluster sampling.

6. Multi-stage Sampling: In multi-stage sampling, the population or area is distributed into a number of first-stage sampling units and a sample is chosen randomly from these first-stage sampling units. Each of these selected units are further sub-divided into second-stage units and again the sample has been chosen. Thus, stratification is done at least four stages to constitute a final sample for the purpose of investigation. 

Non-probability Sampling Methods

In the non-probability sampling methods, the process of selection depends on the investigator’s personal choice. It means he picks up only those items which he thinks are typical or representative of the population.

1. Convenience Sampling: As the name suggests, the process of selection of items depend on the convenience and ease of the investigator i.e., the data which is easily accessible and within his reach.

2. Judgement Sampling: Generally, judgement sampling method is adopted in that case where the qualitative data is used for the purpose to develop hypotheses. In this type of sampling, a representative sample is formed by using the investigator’s judgement for selecting sample items.

3. Quota Sampling: In quota sampling, the population is first segmented into mutually exclusive homogeneous sub-groups, just as in stratified sampling. Then judgement is used to select the subjects or units from each segment based on a specified proportion. For example, an interviewer may be told to sample 200 females and 300 males between the age of 45 and 60.

Quota sampling is useful when time is limited, sampling frame is not available, research budget is very tight or when detailed accuracy is not important.

Subcribe on Youtube - IGNOU SERVICE

For PDF copy of Solved Assignment

WhatsApp Us - 9113311883(Paid)