Definition: The Convenience Sampling is the non-probability sampling technique wherein a proportion of the population is selected on the basis of its convenient availability.
This method is also called the chunk (fraction) taken from the population on the basis of its convenient accessibility and availability to the investigator. The telephone directory, census survey report, automobile registration list is readily available and therefore is a convenience sample and not the random sample, even if the subjects are selected randomly from the list.
The convenience samples are also called as the Accidental Samples because the subjects happen to be selected under study accidently due to their presence at the right place and at the right time when the information for the study is being conducted. For example, the interviewer stops near the office buildings, railway stations, bus stands, etc. to interview people who pass by.
Since the samples are selected conveniently, it is not necessary that these reflect the true attributes or characteristics of the target population. Also, there are several opportunities of personal prejudice or bias of the investigator that can tamper the results. Thus, the level of sampling error is higher in the case of the convenience sampling.
Although the convenience sampling suffers from severe limitations, it is widely used in the public opinion surveys, account auditing and pilot studies. In pilot studies, the preliminary information is collected from people in the form of questions before designing of a complete sampling plan.