 |
| Non-random Sampling Techniques |
Sampling is the process of
drawing a sample from a population. When we sample, we study the characteristics
of a subset (called the sample) selected from a larger group (called the
population) to understand the characteristics of the larger group.
There are random (also called
probability) and non-random (also called non-probability) sampling techniques.
In non-random sampling or non-probability
sampling, the units are selected at the discretion of the researcher. Such
samples use human judgment in selecting units. While selecting the sample, the
researcher only thinks where he will get the required data to serve his
research purpose.
Such samples are used in the
situations where the researcher does not want a representative sample. The
researcher wants to gain insight into the problem by selecting only informed
person who can provide him the maximum degree of insight into his problem with
comprehensive information.
Quota Sampling: In this method, quota of sample from different units of the
population is fixed and thus, total sample is selected.
Convenient Sampling: In this method,
whosoever is available to cooperate for providing information is selected and
thus, the required number of sample is obtained.
Snowball Sampling: It is used to find subjects of interest from those who are
most likely to be able to identify them. In this technique, the researcher uses
few subjects to identify the other individuals who might be appropriate for the
study. This continues with the new subjects, until the researcher has a
sufficient and desired sample size.
Purposive Sampling: In purposive sampling, the researcher specifies the
characteristics of a population of interest and then tries to locate
individuals who have those characteristics. For example, a researcher might be
interested in adult females over the age of 35 who are enrolled in a adult
education program. Once the group is located, the researcher asks those who
meet the inclusion criteria to participate in the research study.
