2. Definition
The researcher has to make a careful selection
of a few elements from the population and
then study them intensely and reach
conclusion, which can be safely applied to the
population. The selection of sample is a very
important task. The researcher should
determine the size of sample, the method of
sampling, the test of sample etc.
5. Simple Random Sampling
Each and every element of the population is
having the equal chance of being selected as
sample. It is biasfree. It is also called
Probability Sampling.
Ex- Lottery system
6. Deliberate Sampling
Sample is collected according to the wish of
the researcher. It is not biasfree. It is also
know as Purposive Sampling.
7. Judgment Sampling
The researcher chooses the sample according
to his/her judgment. Sample is selected based
on opinion of an expert. It is somewhat
biased.
8. Systematic Sampling
All the elements are numbered (1, 2, 3, …., n).
Then random samples are selected.
Ex- Let, total population = 15000
Which are numbered from 1 to 15000.
If 300 people chosen randomly then
Sample = 300
9. Stratified Sampling
This technique is useful when homogeneous
data are not available. Here, the population is
divided into different homogeneous group
which are called strata. Out of different strata
sample is collected randomly.
10. Quota Sampling
It is same as Stratified Sampling but the only
difference is a particular Quota is assigned to
every group.
Ex- A researcher might need a sample of 100 females
or 100 individuals between the ages of 20 – 30.
11. Cluster Sampling
The total element is divided into different
cluster or group and sample is chosen from
cluster.
Ex- Total = 1500
Sample size = 300 or 3 cluster
12. Area Sampling
Total area is divided into small-small areas and
from among then some area are selected
which are sample for data collection Area
sampling.
13. Multistage Sampling
When geographical area is very broad like a
country then Multistage sampling is used.
Ex- Total country is divided into different stage like
districts, villages, for choosing sample.
14. Sequential Sampling
Here, the sample size is not prefixed. The size
of the sample changes according to need of
the statistical measures or it is used for
Statistical Quality Control.