by A finite subset of the population, selected from it with the objective of investigating its properties is called a sample and the number of units in the sample is known as the sample size.
Sampling is a tool which enables us to draw conclusions about the characteristics of the population after studying only those objects or items that are included in the sample. The main objectives of the sampling theory are:
(i) To obtain the optimum results, i.e., the maximum information about the characteristics of the population with the available sources at our disposal in terms of time, money and manpower by studying the sample values only.
(ii) To obtain the best possible estimates of the population parameters.
Some critical essentials of sampling include:
- Representativeness: You must select the sample in a manner which represents the universe in its truest sense. Further, if you fail to do so, then you might get misleading results.
- Adequacy: You should also select the size of the sample adequately which represents the parametric characteristics of the population.
- Independence: When you select a sample, you must ensure that you select the items independently and also randomly.
- Homogeneity: This is another important element of a sample investigation. Homogeneity means that there is no basic difference in the nature of the units in the sample and the universe.
Some important merits of sampling:
- Cost-efficient: In a sample investigation, the costs associated with the collection of data are less. This is because you collect data only from a fractionof the entire population. Therefore, it is cost-efficient.
- Time-efficient: In sampling, you require less time to collect, analyze, and interpret the data since you are working only on a fraction of the population. Hence, it is time-efficient too.
- Reliable: Usually, the data collected under a sample investigation is reliable because of the use of well-trained and experienced investigators or experts.
- Flexible: When you collect data through sampling, you have a greater scope of flexibility.
- Detailed Information: Since sampling is cost-efficient and also time-efficient, you can collect detailed information about the sample in your survey.
