What Is Quota Sampling?

In quota sampling, the population is first segmented into mutually exclusive sub-groups, just as in stratified sampling. Then judgment is used to select the subjects or units from each segment based on a specified proportion. For example, an interviewer may be told to sample 200 females and 300 males between the age of 45 and 60. In quota sampling the selection of the sample is non-random.

Quota sampling a second type of purposive sampling ensures that certain groups are adequately represented in the study through the assignment of a quota. Generally the quota fixed for each subgroup is based on the total numbers of each group in the population. However since this is non probability sampling plan the results are not generalizability in the population.

Quota sampling can be considered as a form of proportionate stratified sampling in which a predetermined proportion of people are sampled from different groups, but on a convenience basis. For instance it may be surmised that the work attitude of blue-collar workers in an organization is quite different from that of whit collar workers. If there are 60 percent blue collar workers and 40 percent white collar workers in this organization and if a total of 30 people are to be interviewed to find the answer to the research question then a quota of 18 blue-collar workers and 12 white-collar workers will form the sample because these numbers represent 60 percent and 40 percent of the sample size. The first 18 conveniently available blue-collar workers and 12 white-collar workers will be sampled according to the quota.  Needless to say the sample may not be totally representative of the population.