Write down the advantages and disadvantages of Sampling.

Ans.

Importance of Sampling in our daily life

In practice the sampling technique of investigation is a very important and popular method. Its use is not limited to scientific and technical investigations only but it is widely used in different activities of our day-to-day life. A grain merchant takes decision about the quality of wheat just by taking a handful sample from a big lot. A housewife examines just on the basis of one or two potato from the lot of boiling potatoes whether they have boiled or not? The study of student of the whole year is tested just by an examination of three hours, Snedecor observes, “A carload of coal is accepted or rejected on the evidence gained from testing only a few pounds. The physician makes inferences about a patient’s blood through examination of single drop. Samples are devices for learning about large masses by observing a few individuals.” Roy W. Jestram has observed to this extent that “it is indeed a great scientific achievement towards an intellectual mastery of the world around as to generalise logically and precisely about thousands of values which we have not seen, simply upon the evidence afforded by, say, 50 or a 100 of those values.” The fact is that we are living in the age of sampling.

Merits

(1) Economic Method: This method is much more economical than a complete census because only a fraction of the population is studied in this method.

(2) Saving of Time and Labour: There is saving in time. and labour not only in conducting the sampling enquiry but also in the processing, editing and analysing the data.

(3) Testing of Accuracy: The accuracy of sampling investigation can be tested by comparing the results of two or more samples. If samples are drawn on the basis of random sampling, their errors can also be estimated.

(4) Detailed and Intensive Enquiry: In this method the number of units under study is kept limited and this makes it possible to study them in detail and intensively.

(5) Reliability: If samples are taken in proper size and on proper grounds the results of sampling will be almost the same which might have been obtained by census method.

(6) Only Method in many cases: In certain circumstances sample enquiry is the only method of investigation. If the population is infinite or too large, then sampling is the only way of estimating the parameters of a population. Similarly, if the testing of units is destructive, then also we are left with no other way but to use sampling i.e., to estimate the average life of the bulbs or to test the quality of crackers, etc.

(7) Administrative Convenience: The organisation and administration of sample survey is relatively much convenient.

Demerits

(1) Misleading results : If a sample survey is not properly planned and carefully executed, the results obtained may be unreliable and misleading. In this context Frederick F. Stephen observes, “Samples are like medicines. They can be harmful when they are taken carelessly or without knowledge of their effects.”

(2) Need of specialised knowledge: An efficient sampling requires the services of qualified, skilled and experienced personnel. In the absence of these the results of the survey may not be reliable.

(3) Heterogenous Units: If the units of population are too heterogenous, the sampling technique cannot give fair results.

(4) Impossibility of Sampling: Sometimes the universe may be so small that it may be impossible to draw a representative sample from it.