This document discusses different sampling methods used in research. It describes probability sampling methods like simple random sampling, systematic sampling, stratified sampling, cluster sampling, and multi-stage sampling. It also describes non-probability sampling methods like convenience sampling, purposive sampling, and snowball sampling. The key aspects of each sampling method are defined along with their advantages and disadvantages. Probability sampling aims to ensure that samples are representative of the larger population, while non-probability sampling does not allow determining the probability of sample selection.

1. Sampling methods
submitted by
Anju. K.J

2. sampling
 The process of selecting a number of individuals for a study in such a way that the
individuals represent the larger group from which they were selected
 Sampling is the process of selecting observation(samples)to provide adequate and
inference of the population

6. Types of sampling
Probability sampling Non probability sampling

7. Probability sampling
 It is the method of sampling in which each element has known probability
of being included in the sample
 Types of probability sampling
1.simple random sampling
2.stratified random sampling
3.systematic sampling
4.multi stage sampling
5.cluster sampling

8. Simple Random Sampling
 Selecting subjects so that all members of a population have an equal and
independent chance of being selected
 It can be done by drawing the names out of a container until required number is
reached
 There are two types :-simple random sampling with replacement
simple random sampling without replacement

9. Simple random sampling
 Advantages
1. Easy to conduct
2. High probability of achieving a representative sample
3. Meets assumptions of many statistical procedures
 Disadvantages
1. Identification of all members of the population can be difficult
2. Contacting all members of the sample can be difficult

10. Systematic sampling
 It is modified form of simple random sampling
 It involves selecting a random element and then every nth element is selected until
desired number of sample required
 For eg:- from population of 2000 if a sample of 100 is required ,then every 20th
person can be selected
 If N is the total number of the wider population and “sn” is the required number in
sample ,then “f” the frequency interval can be calculated as
f=N/sn

11. Systematic sampling
 Advantages
1.Moderate cost
2.Simple to draw the sample
 Disadvantages
1.Periodic ordering required

12. Stratified sampling
 It is the two stage process
1.Devide the wider population into homogeneous(by identifying their characteristic)
2.Randomly select the sample within the groups
 Homogeneous groups are known as strata
 https://youtu.be/47bYUQ4Ueb8

13. Stratified sampling
 Proportionate random sampling-select cases in such a way that
ensure the same proportion from each stratum in the sample
 Population:4% black,25%latino,27%Asian,44%white
 In sample of 1000:40 black,250latino,270Asian ,440 white
 Disproportionate random sampling-proportion selected from each
stratum is not the same as in the population
 Population:4% black,25%latino,27%Asian,44%white
 In sample of 1000:250 black,250latino,250Asian ,250 white

15. Cluster sampling
 It is sample technique in which the population is divided in to clusters.
Clusters are heterogeneous intact group of members of the population
 Then a sample of cluster is selected randomly from these clusters
 It is used when population is large
 Eg:- area sampling

16. Cluster sampling
 Advantages
1.Lower field/resource cost
2.Enable sampling of groups of individual for which detail on
individual themselves may not be available
 Disadvantages
1.Lowest precision
2.Introduce more complexity in analysing data

18. Multi stage sampling
 It is the sampling method in which various sampling methods are
used in different stages of sampling
 Eg :-a national polling service may stratify the country by
geographical region, select a random sample of cities from each
region and then interview a cluster of residence in the city

19. Multi-stage sampling
 Advantages
1.More accurate
2.More effective
 Disadvantages
1.Costly
2.Each stages in sampling introduce errors, so more stages more error
will occur

20. Non probability sampling
 non probability sampling does not allow the researcher to
determine the probability of each element to be in he sample
Types of non probability sampling
 Incidental sampling
 Purposive sampling
 Judgmental sampling
 Snowball sampling

21. Incidental/convenience sampling
 The sampling involves selection of nearest individual or those whom the
researcher meet in sample
 It is the process of picking up the people in most convenient and fastest way to
immediately get their reaction to a certain or controversial issues
 Not representing target population because samples are selected if they can be
assessed easily and conveniently
 It could deliver accurate result only when the population is homogeneous
 Advantage –easy to use
 Disadvantage-bias is present

22. Purposive/judgmental sampling
 The samples are selected for a particular purpose
 It is often featured in qualitative research
 For example, if the researchers want to study about the factors
leads to sickle cell anaemia ,the only people to be consulted for first
hand information are medical doctors who are treating such people

23. Purposive sampling
 Advantages
1.Flexible
2.Facilitate the purpose of study
 Disadvantages
1.Biased
2.Not reliable
3.Inaccuracy and inability in generalisation

24. Snowball sampling
 A sampling technique in which the existing subject recruits the future
subjects from their acquaintances
 Sample group appears t grow like rolling snowball, as the sample built
ups the enough data gathers from it
 Used for hidden population like drug users, persons with socially
unacceptable behaviour, commercial prostitutes

25. Snowball sampling
 ADVANTAGES
 The chain referral process allows the researcher to reach populations that are difficult to
sample when using other sampling methods
 Cheap, simple and cost-efficient
 Little planning and fewer workforce compared to other sampling techniques
 DISADVANTAGES
 Little control over the sampling method
 Representativeness of the sample is not guaranteed

27. Thank you……..