Ans. A survey is referred to as the ‘Census’ or ‘Method of Complete Enumeration’ where every element of the population is included. On the other hand, sampling occurs when a subset of the population is studied and predictions about the entire population are made based on this subset. Census is more accurate in terms of results because it studies all units of population, but it is time consuming, expensive, and sometimes not feasible to use. As a result, sampling is preferable for the following reasons:
(i) Economical – Because sampling involves studying a subset of the population, the cost of sampling is relatively low. Census costs are high, especially when the population is large and the area covered is extensive.
(ii) Time savings – A census survey takes a significant amount of time if the population is large or spread out over a large area, whereas sample studies do not.
(iii) Less effort – Because only a subset of the population is studied, the investigator must expend less effort than in a census.
(iv) Census Inappropriacy – When the population is infinite or exhaustible, census cannot be performed, and sampling is the only option. For example, one cannot burn all of the units of coal available to determine their calorific value; a sample is the only way to test it.
(v) Considerable accuracy – Although the results of sampling may not be as accurate as in the case of sampling, the level of accuracy of these results can be established through statistical tests of significance and thus can be applied in general to the entire population if significant.