Cost: By comparison with a complete enumeration of the same population, a sample may be based on data for only small number of the units comprising that population. A sample survey may thus be very much less expensive to conduct than a comparable complete enumeration.
Time: Being small in scale, a sample survey is not only less expensive than a census; the desired information is obtained in much less time.
Scope: The smaller scale is likely to; permit the collection of a wider range of survey data and allow a wide choice of methods of observations, measurements or questioning than is usually feasible with a complete enumeration.
Respondents Convenience: The sample survey considerably reduces the overall burden of the respondents in the way that only a few, not all of the individuals in the population are put to the trouble of having to answer questions or provide information.
Labor: Sampling saves labor. A small staff is required both for fieldwork and for tabulation and processing data.
Flexibility: In certain types of investigation, highly skilled and trained personnel or even specialized equipment are needed to collect data. A complete enumeration in such cases is impracticable and hence sample surveys, being more flexible and greater scope, will be more appropriate for this type of inquires.
Data Processing: The data-processing requirement for a sample survey is likely to be much less than for a complete count. Whereas a complete count may well require a computer to process the data, a sample survey can often be processed manually with fewer people and less logistic supports.
Accuracy: A sample survey employs personnel of higher quality equipped with intensive training and supervision that is more careful is possible for fieldwork. As a result, observations, measurements, equipments, or questioning for a sample survey can often be carried out more carefully and thus yields results subject to similar non-sampling error than is generally practicable in a more extensive complete enumeration, usually at a much lower cost.
Feasibility: there are situations where complete enumeration is not feasible and thus a survey is necessary. There is also instance where it is not practicable to enumerate all the units due to their perishable or fragile nature. The alternative in this situation is to take only a few of the units. For example, consider the problem of checking the quality of mango juice produced by a local company. One way to test the quality is to drink entire lot, which is impracticable. Testing of electric bulb, screws, glass, medicine all are example of this type, where sampling is necessary.
Limitations of Sample Survey
Despite several advantages of sample survey over complete count, it has some disadvantages or limitations too. The results of a sample survey are subject to sampling error, and on that account are less precise than those of an otherwise comparable complete enumeration are. Moreover, by chance alone, a sample may seriously over-represent, under –represent or even fail to represent in frequently occurring sub-groups of a population. In such instances, the estimates provided by such surveys are liable to larger margin of errors.
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