What are the steps involved in a sampling Design?(May 18) (10Marks)

Q What are the steps involved in a sampling Design?(May 18) (10Marks)

ANS: While developing a sampling design, the researcher must pay attention to the following points:

(i) Type of universe: The first step in developing any sample design is to clearly define theset of objects, technically called the Universe, to be studied. The universe can be finite or infinite. In finite universe the number of items is certain, but in case of an infinite universe the number of items is infinite, i.e., we cannot have any idea about the total number of items. The population of a city, the number of workers in a factory and the like are examples of finite universes, whereas the number of stars in the sky, throwing of a dice, etc. are examples of infinite universes.

(ii) Sampling unit: A decision has to be taken concerning a sampling unit before selecting sample. Sampling unit may be a geographical one such as state, district, village, etc. The researcher will have to decide one or more of such units that he has to select for his study.

(iii) Source list: It is also known as ‘sampling frame’ from which sample is to be drawn. It contains the names of all items of a universe (in case of finite universe only). If source list is not available, researcher has to prepare it. Such a list should be comprehensive, correct, reliable and appropriate. It is extremely important for the source list to be as representative

of the population as possible.

(iv) Size of sample: This refers to the number of items to be selected from the universe to

constitute a sample. This a major problem before a researcher. The size of sample should

neither be excessively large, nor too small. It should be optimum. An optimum sample is

one which fulfills the requirements of efficiency, representativeness, reliability and flexibility.

While deciding the size of sample, researcher must determine the desired precision as also

an acceptable confidence level for the estimate.

(v) Parameters of interest: In determining the sample design, one must consider the question

of the specific population parameters which are of interest. For instance, we may be

interested in estimating the proportion of persons with some characteristic in the population,

or we may be interested in knowing some average or the other measure concerning the

population.

(vi) Budgetary constraint: Cost considerations, from practical point of view, have a major

impact upon decisions relating to not only the size of the sample but also to the type of

sample. This fact can even lead to the use of a non-probability sample.

(vii) Sampling procedure: Finally, the researcher must decide the type of sample he will use

i.e., he must decide about the technique to be used in selecting the items for the sample.