Sunday 19 February 2017

Non-random Sampling Techniques

Non-random Sampling Techniques
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.