Quota Sampling is one kind of purposive or judgment sampling. A quota sample is one in which the investigator is directed to collect information from an assigned number or quota of individuals, in each of the several groups characterized in the universe.
The investigators select respondents within the quota according to their judgment.
Different criteria may be adopted in selection of sample observations. However, the units selected in each group are based on the interviewer’s choice rather than being decided on the basis of probability methods.
The quota sampling technique is very popular in opinion surveys and market studies. In the light of greater flexibility in selection of sample units, the investigator is free to draw units of his choice without adopting the rules of random sampling.
This technique involves the risk of personal prejudice and presence of bias. Hence, quota sampling is not widely suggested in practical work.
This technique has two important sources of error:
(i) the quotas prescribed for the interviewer represent a crude stratification of the universe
(ii) the principle of convenience is adopted by the investigator in selecting sampling observations.
For example we have a population of three categories, i.e., Rich, Medium and Poor. These are given in the ratio 20%, 30%, 50% respectively. Using quota sampling determines the number of representatives for each category of a sample size of 200.
The investigators select respondents within the quota according to their judgment.
Different criteria may be adopted in selection of sample observations. However, the units selected in each group are based on the interviewer’s choice rather than being decided on the basis of probability methods.
The quota sampling technique is very popular in opinion surveys and market studies. In the light of greater flexibility in selection of sample units, the investigator is free to draw units of his choice without adopting the rules of random sampling.
This technique involves the risk of personal prejudice and presence of bias. Hence, quota sampling is not widely suggested in practical work.
This technique has two important sources of error:
(i) the quotas prescribed for the interviewer represent a crude stratification of the universe
(ii) the principle of convenience is adopted by the investigator in selecting sampling observations.
For example we have a population of three categories, i.e., Rich, Medium and Poor. These are given in the ratio 20%, 30%, 50% respectively. Using quota sampling determines the number of representatives for each category of a sample size of 200.
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