220.127.116.11 Convenience Sampling
A convenience sample is obtained by selecting ‘convenient’ population units.
The method of convenience sampling is also called the chunk. A chunk refers to that fraction of the population being investigated which is selected neither by probability nor by judgment but by convenience. A sample obtained from readily available lists such as automobile registrations; telephone directories, etc., is a convenience sample and not a random sample even if the sample is drawn at random from the lists. If a person is to submit a project report on labour-management relations in processing industry and he takes a processing industry close to his office and interviews some people over there, he is following the convenience sampling method. Convenience samples are prone to bias by their very nature—selecting population elements which are convenient to choose almost always make them special or different from the best of the elements in the population in some way.
Hence the sample obtained by the convenience sampling method can hardly be representative of the population—they are generally biased and unsatisfactory. However, convenience sampling is often used for making pilot studies. Questions may be tested and preliminary information may be obtained by the chunk before the final sampling design is decided upon.