1. SAMPLING
J.RAJEES Assistant Professor Department Of Commerce Computer Application St.Joseph’s College (Autonomous) Tiruchirappalli

2. SAMPLING
Definition : “ a sample is a smaller representation of a larger whole” -Goode and Hatt “samples are devices for learning about large masses by observing a few individuals” Snedecor

3. Why sampling is used Economical Less time consuming Reliability
Detailed study
Sampling is a scientific technique
Greater suitability

4. Objectives of sampling
To make an inference about an unknown parameter from a measurable sample
To test the hypotheses relating to population
To avoid the vast study about the entire population
To obtain quick result

5. Characteristics of a good sampling
Representativeness
Independence
Adequacy
Homogeneity

6. Steps taken to make the sample useful and reliable
Defining the population
Specifying the sampling frame
Specifying the sampling unit
Specifying the method of sampling
Determining the size of sample
Specifying the sampling plan
Selection of sample

7. Types of sampling methods
Probability sampling (or)random sampling
Non probability sapling (or ) non random sampling

8. Probability sampling
Random Unrestricted random sampling (or) simple random sampling
Lottery method
Random number method
Restricted random sampling
Stratified random sampling
Systematic sampling
Cluster and area sampling
Multi stage sampling
Sequential sampling

9. Lottery method
Lottery method of sampling refers to the process of drawing a lot among the population or universe. Under this method the required number of samples are selected from the total population by blindfold from the drum or urn.

10. Random number method
This method is an alternative to lottery method. Samples are drawn by using the table of random numbers. The random numbers are generally obtained by some mechanism that could be expected in a random sequence of the digits 0 to 9

11. Standard tables of random sample
Tippett’s (1927) random number tables consisting of 41,600 random digits. Fisher and Yates (1938) table of random numbers with 15,000 random digits. Kendal and Babington Smith (1939) table of random numbers consisting of 1,00,000 random digits. C.R.Rao, Mitra and Mathai(1966) table of random numbers.

12. Restricted sampling method
Under this method the size of the population is restricted to normal size on the basis of certain characteristics.

13. Methods of obtaining restricted random sample
Stratified random sampling
Systematic sampling
Cluster and area sampling
Multi stage sampling
Sequential sampling

14. Stratified random sampling
Under this method the population is divided in to some groups or classes(stratum) based on their homogeneity and samples are drawn from each stratum at random .

15. Systematic sampling
Under this method the universe is arranged on the basis of some systems. (alphabetical , numerical , geographical etc.,)
Sampling internal (or) K size of population =
size of sample

16. Cluster and area sampling
Cluster sampling refers to the procedure of dividing population into groups called clusters and samples are drawn from these clusters.

17. Multistage sampling
Multi stage sampling is a type of sample design in which some information is collected from the whole sample and additional information is also collected from sub sample of the full sample.

18. Sequential sampling
Under this method , the size of the sample units is not determined in advance , but fixed according to mathematical decision rules based on the survey. This is usually adopted in case of acceptance sampling plan in context of statistical quality control.

19. NON PRABABILITY SAMPLING
Convenience sampling
Judgment (or) purposive sampling
Quota sampling

20. Convenience sampling
This method also called as chunk method which means to the fraction of population to be invested
Eg. Sample obtained from readily available list such as car booking , telephone directories , etc.,

21. Purposive sampling
Under this method the samples are drawn on the basis of personal judgment of a person.

22. This method is adopted in the market survey
Quota sampling
This method is adopted in the market survey

23. THANK YOU