This document discusses different types of sampling methods used in research. It describes probability sampling methods like simple random sampling, stratified sampling, cluster sampling, and systematic sampling which give each unit an equal chance of being selected. It also describes non-probability sampling methods like convenience sampling, quota sampling, judgmental sampling, and snowball sampling where units are chosen non-randomly based on accessibility or the researcher's judgment. The document explains the advantages and disadvantages of each sampling method for research purposes.

1. Presented by-
Sangeeta Raj Singh
Sampling
and its types

2. Sampling
Sampling means selecting a particular group or sample to represent the entire population.
A sample refers to a smaller manageable version of a larger group.
Sample- It is a unit that is selected from population.
Represents the whole population.
purpose the draw the inference.
Why sample??
Sampling frame- listing of population from which a sample
is chosen.

3. Types of Sampling
Sampling
Probability sampling
 Simple random sampling
 Stratified sampling
 Cluster sampling
 Systematic sampling
 Multistage sampling
Non Probability Sampling
 Convenient sampling
 Judgmental sampling
 Quota sampling
 Snow ball sampling
.

4. PROBABILITY SAMPLING
Probability sample is a technique which every units in the population
has equal chance or has a chance of being selected in the sample
accurately determined its also calls non zero chance.

5. SIMPLE RANDOM SAMPLING
All subsets of the frame are given an equal probability.
Random number generators.
Unbiased .
Advantages-
Minimal knowledge of population needed
Easy to analyze data.
Disadvantages-
Low frequency of use .
Does not use researchers’ expertise.
Larger risk of random error.

6. STRATIFIED RANDOM SAMPLING
Population is divided into two or more groups called strata.
Subsample are randomly selected from each strata.
In stratified sampling the sampling frame is divided into homogeneous and non overlapping sub groups or strata.
Type-
Proportional stratified sampling.
Non- proportional stratified sampling.
Advantages-
Assure representation of all groups in sample population.
Characteristics of each stratum can be estimated and comparisons made.
Disadvantages –
Requires accurate information on proportions
of each stratum
Stratified lists costly to prepare.

7. Cluster sampling
The population is divided in to subgroups (clusters) like families.
A simple random sample is taken from each cluster.
Advantages-
can estimate characteristics of both cluster and population.
Disadvantages-
The cost to reach an elements to sample is very high.
Each stage in cluster sampling error- the more stages there
are, the more error there tends to be.

8. Systematic sampling
Order all units in the sampling frame.
Then every nth number on the list is selected.
N= sampling interval
Advantages-
Moderate cost; moderate usage
Simple to draw sample
Easy to verify
Disadvantages-
Periodic ordering required.

9. Multistage sampling
Carried out in stages.
Using smaller and smaller sampling units at each stage.
Advantages-
More accurate
More effective.
Disadvantages –
Costly.
Each stage in sampling introduces sampling
error there tends to be.

10. Non probability samples
The probability of each case being selected from the total population is not known.
Units of the sample are chosen on the basis of personal judgement or convenience.
There are no statistical techniques for
measuring random sampling error
in non- probability sample.

11. Convenience sampling
Convenience sampling involves choosing respondents at the convenience of the researcher.
Its also known as accidental or opportunity sample. A sample is draw from that part of
population which is closed to hand readily available or convenient.
Advantages-
very low cost
Extensively used/understood
Disadvantages-
Variability and bias cannot be measured or controlled
Project data beyond sample not justified.
Restriction of generalization.

12. Quota sampling
The population is first segmented into mutually exclusive sub-group, just as in stratified sampling.
Quota sampling are two types-
1. Proportional quota sampling.
2. Non-proportional quota sampling.
Advantages-
Used when research budget limited
Very extensively used/ understood
No need for list of population elements.
Disadvantages-
Variability and bias cannot be measured/ controlled
Time consuming
Projecting data beyond sample not justified.

13. Judgmental sampling
Researcher employs his or her own expert judgment about.
Researcher choose only those sample or people they fit for demand of research.
e.g.- choosing skilled candidates for vacancy.
Advantages-
There is assurance of quality response.
Meet the specific objective.
Disadvantages-
Bias selection of sample may occur.
Time consuming.

14. Snowball sampling
The research starts with a key person and introduce the next one to become a chain.
e.g. - Acid attack victim.
Advantages-
Low cost.
Useful in specific circumstances & for
locating rare populations.
Disadvantages-
Not independent.
Projecting data beyond sample not justified.