This document discusses different sampling methods used in research studies. It describes probability sampling methods like simple random sampling, systematic sampling, and stratified sampling which involve random selection. It also covers non-probability sampling techniques such as judgmental sampling, accidental sampling, quota sampling, and convenience sampling which do not use random selection. The key advantages of sampling over a census are lower cost, faster data collection, and feasibility when the entire population cannot be studied. However, sampling results in less accuracy than a census due to potential errors.

1. SAMPLING & CENCUS
Probability & Nonprobability
Sampling
Presented by:
Anu Thapa(700408)
Navin Mandal(700415)
Rupesh Chaudhary(700420)

2. SAMPLING
INTRODUCTION
The few selected unit is called sample and
the method of selecting the sample is
called sampling.
process of selecting sample from the
universe or target population by the
researchers

3. .
TARGET POPULATION OR UNIVERSE
The population to which the investigator
wants to generalized his results
SAMPLING UNIT
Smallest unit from which sample can be
selected

4. Demerits of sampling
technique
Less accuracy
Misleading conclusion
Needs for specialized knowledge
When sampling is not possible
In case of :-
oWhen 100% accuracy is required
oThe population is heterogeneous
o When population is very small

5. Why Sample?
Get information about large populations
Lower cost
More accuracy of results
High speed of data collection
Availability of population elements.
Less field time
When it’s impossible to study the
whole population

6. Sample Vs. Census
Sample
 Only few units of the
population is studied
 It is most suitable if
population is
homogeneous
 There is margin for
error
 Take less time man
power and money
 This is smaller in
proportion
Census
 each and every unit of
the population is
studied
 It is most suitable if
population is
heterogeneous
 It is more accurate
 Take more time man
power and money
 This is much bigger in
proportion

7. Method of Sampling
.
Method of
Sampling
Probability
Sampling
Non-
Probability
Sampling

8. Probability Sampling
 Scientific method of selecting sample
 Each unit of population has equal chance of
selection
Non-Probability Sampling
 Does not involve random selection and methods
 are not based on the rationale of probability
theory.

9. Types of probability sampling
1. Simple Random Sampling (SRS)
 Simplest method of sampling
 A random no. table or lottery method is used
to determine which units are to be selected.
 Types
oSimple random sampling without replacement
(Srswor)
oSimple random sampling with replacement (Srswr)

10. Example :
Suppose a population consists of 18 units
and a sample size of 5 is to be selected.
From the random table or lottery method,
selected random no. are 65,43,63,54,46
65/18,43/18,62/18,54/18,46/18
11,7,8,0,10:- selected as sample

11. 2.Systematic Sampling
Obtain the information from cards or
register which are in serial order.
Example: Suppose a population consists
of 440 units and a sample size of 40 is to
be selected.
K=
𝑁
n
=
440
40
=11
J=6 (Random no. taken between 1 to 11)
Now,
J,J+K,J+2K,J+3K…………………J+39K
6,17,28,39,………………………..,435
Every 11th person is selected from a list of all
population.

12. 3.Stratified Sampling
 The population is divided into two or more
groups called strata,
 according to some criterion, such as
geographical location, grade level, age,
gender or income.
 and subsamples are randomly selected from
each strata.
 Each stratum is more homogeneous then the
total population
 Stratified sampling results in more reliable
and details information

13. Types of Non –Probability
Sampling
1. Judgmental Sampling
 Based on experience & qualification of
researchers.
 This sampling also known as purposive
sampling.
 If the researcher is experience an experts it is
possible that judgment sampling may useful
results.
2. Accidental Sampling
 Pedestrian are used as sample in accidental
 This is very economical

14. .
3.Quota Sampling
 Quota is directly proportional to the size of
stratum.
4.Sequencing Sampling
 Sequencing sampling also known as acceptance
of sampling
 Sample is accepted when it confirms
specifications
5. Convenience sampling
 Telephone Sampling
 197

15. Sample Error
Sample Error (E)=
𝝈
𝒏
Where, E = Sample Error
𝝈 = Standard of Deviation
n = Sample Size
 If Sample size is less then chance of error will be
more.
 If sample size more then there will be more
wastage and Uneconomical.
 There for optimum size of sample will be selected.

16. THANK YOU
.