Purposive Sampling

A non-probability sampling method that conforms to certain criteria is called purposive sampling. There are two major types of purposive sampling:


(i) Judgment Sampling (ii) Quota Sampling

(i) Judgment Sampling: Judgment sampling or expert choice is one in which cases are included for investigation through a planned selection procedure.

In judgment sampling procedure are selected who are considered to be most representative of the population as a whole. It is a sampling because choice of the individual units depends entirely on the sampler, who, on his own judgment, decides the sample to be selected that conforms to some criteria. In a study of labor problem, you may decide to talk only with those who have experienced discrimination while they were in job. Election results are predicted from only few selected persons because of their predictive in past elections.

(ii) Quota Sampling: Another type of non-probability sampling is (ii) quota sampling. This technique is widely used by market researcher, political opinion seekers and many others to avoid the cost problems of interviewing a pre-selected sample of individuals. In this method, individual are not pre-selected at all, but once strata are formed (usually based on sex, age, social status, region of residence etc.), general breakdown of the sample is decided (e.g. how many men and how many women, how many persons in each age group or in each sex category or social class is to include) and quota assignments are allocated to the interviewers, selection of the individuals within the strata is left to the interviewers with whom they are to conduct interviews. The factors sex, age, social status etc., which are used to form strata, are termed ‘Quota Control’.