TYPES OF SAMPLING

Fundamentally, there are two types of sampling methods:

(a)    Probability Sampling Method and

(b)   Non-probability Sampling Methods.

In case of: (a)   Probability Sampling Method

i)       The probability or chance of every unit in the population being included in the sample is known.

ii)         Selection of the specific units in the sample depends entirely on chance.

iii)    No substitution of one unit for another is permissible and hence no human judgment or bias on account of this is possible.

iv)   It is possible to measure the sampling error and hence we can know the degree of precision.

v)     The use of probability sampling also enables us to determine the sampling size for a given degree of precision and also enable us to choose a representative sample.

vi)  As probability sampling helps in selection of a representative sample and gives the degree of precision, this helps in building up confidence in the inference.

vii) Various techniques of probability sampling are: (i) Simple Random Sampling, (ii) Systematic Sampling, (iii) Cluster Sampling, (iv) Multistage and Multiphase Sampling

(b)   Non-Probability Sampling Method

i)    In a non-probability sample, the probability of indecision of any unit (of population) in a sample is not known.

ii)  The selection of units within a sample involves human judgment rather than pure chance.

iii) The maximum information available “per rupee” which can be determined from a probability sample is not possible in this case and moreover, the degree of accuracy is not known.

iv)  Although the probability sampling is scientific and gives the accuracy involved, however, because of convenience and economy, the non-probability samples are preferred as compared to probability samples.

v)   Many times, samples are selected by interviewers “at random” meaning that the actual sample selection is left to the choice of the researcher, such samples are non-probability samples and not probability samples.

Various techniques used in non-probability sampling methods: 1. Judgment Sampling 2. Quota Sampling 3. Convenience Sampling

SAMPLING TECHNIQUE (1)  Probability Random Sampling (a)    Simple Random Sampling (b)      Stratified Random Sampling  (c)    Systematic Sampling (d)  Cluster Sampling (e)  Multistage Sampling 
2) Non-probability Sampling Techniques (a) Deliberate Sampling (b)  Quota Sampling (c)Convenience Sampling