A detailed explanation of non-probability sampling and its methods have been covered. There are 4 types of non- probability sampling methods: 1. convenience sampling 2. purposive sampling 3. quota sampling (both controlled and uncontrolled) 4. snowball sampling (all 3 ways of performing) Meaning with adequate examples, pros and cons have been covered For and query or further information, Kindly contact: Arpit Surana https://www.linkedin.com/in/arpitsurana116/ arpitsurana116116@gmail.com

1. NON -
PROBABILITY
SAMPLING

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3. NON – PROBABILITY SAMPLING
Non-probability sampling is a sampling technique where the odds of any
member being selected for a sample cannot be calculated. It’s the opposite
of probability sampling, where you can calculate the odds.
For example, one person could have a 10% chance of being selected and
another person could have a 50% chance of being selected. It’s non-
probability sampling when you can’t calculate the odds at all
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5. WHEN? WHY? TO USE NON-
PROBABILITY SAMPLING
1. This type of sampling can be used when demonstrating that a particular
trait exists in the population.
2. It can also be used when the researcher aims to do a qualitative, pilot or
exploratory study.
3. It can be used when randomization is impossible like when the population
is almost limitless.
4. It can be used when the research does not aim to generate results that will
be used to create generalizations pertaining to the entire population.
5. It is also useful when the researcher has limited budget, time and
workforce. 5

6. Advantages
Possibility to reflect the
descriptive comments about
the sample
Cost-effectiveness and time-
effectiveness
Effective when it is unfeasible
or impractical to conduct
probability sampling
PRONS & CONS
Disadvantages
Unknown proportion i.e. lack of
representation of the entire
population
Lower level of generalization of
research findings compared to
probability sampling
Difficulties in estimating
sampling variability and
identifying possible bias
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7. 7
Non-
Probability
Sampling
Conven-
ience
sampling
Purposive
sampling
Quota
sampling
Snowball
sampling
4 Methods

8. CONVENIENCE
SAMPLING
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Also know as Accidental Sampling

9. “In convenience sampling no
inclusion criteria identified prior
to the selection of subjects. The
sample is selected in anyway for
the sake of easiness and
convenience
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11. EXAMPLES
▰ Facebook polls
▰ Pepsi Challenge
▰ Feedback system in big companies
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12. Advantages
Simplicity of sampling and the
ease of research
Helpful for pilot studies and for
hypothesis generation
Data collection can be done in
short duration of time
Cheapest to implement
PRONS & CONS
Disadvantages
Highly vulnerable to selection
bias and influences beyond the
control of the researcher
High level of sampling error
Studies that use convenience
sampling have little credibility
due to reasons above
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13. PURPOSIVE
SAMPLING
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2
Also known as judgment, selective or
subjective sampling

14. “The researchers or experts
obtain a representative sample
by using a sound judgment,
which will result in saving time
and money
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16. EXAMPLES
▰ TV reporters stopping certain individuals on
the street in order to ask their opinions about
GST on insurance (this can be asked to only
to an educated man).
▰ A study of importance of exposure in
colleges (this can be asked to only those
students who has experienced exposure in
college).
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17. Advantages
Cost-effective and time-
effective
Requires limited number of
primary data sources
One of the most time-effective
sampling methods available
PRONS & CONS
Disadvantages
Vulnerability to errors in
judgment by researcher
Low level of reliability and high
levels of bias.
Inability to generalize research
findings
.
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18. QUOTA
SAMPLING
18
3
It has two types controlled and
uncontrolled

19. “A method of gathering
representative data from a group
to ensure that sample group
represents certain features of
the population chosen by the
researcher.
1919

20. HOW TO PERFORM QUOTA SAMPLING
1. Dividing the population into specific
groups
Virgin Media employees in the UK as the
sampling frame need to be divided into
the following five groups according to
their cultural background:
European, Asian (India), Asian (China),
Black (African) and Other
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2. Calculating a quota for each group
Suppose you take 30 representatives
from each group making total of 150.
3. Determine specific condition(s) to be
met and quota in each group
Both genders, males and females need
to be represented equally i.e. 15 each.

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22. Advantages
Quota sampling is good when
you are pressed for time, since
primary data collection can be
done in shorter time
This sampling method can save
costs and time.
It can also be done in absence
of sampling frame
PRONS & CONS
Disadvantages
We can’t calculate sampling
error and the projection of the
research findings
There is disproportionately
represented in the final sample
group
It may suffer from researcher
incompetency and/or lack of
experience
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23. 2 TYPES QUOTA SAMPLING
Uncontrolled sampling, in this
the researcher is free to choose
sample group members
according to his/her will.
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Controlled Uncontrolled
Controlled sampling involves
introduction of certain
restrictions in order to limit
researcher’s choice of samples.

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25. SNOWBALL
SAMPLING
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4
Also known as cold-calling, chain,
chain-referral, and referral sampling.

26. “Snowball sampling is where
research participants recruit
other participants for a test or
study. It is used where potential
participants are hard to find
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27. INTERESING NAME !!
It’s called snowball sampling
because (in theory) once you
have the ball rolling, it picks
up more “snow” along the
way and becomes larger and
larger.
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29. EXAMPLES
▰ A study on investigating cheating on exams
▰ Company that involves primary data
collection from employees of that company.
▰ Mostly used in taking surveys with the help of
questionnaire.
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30. 3 PATTERNS OF SNOWBALL
SAMPLING
Exponential non-
discriminative snowball
sampling
The first subject recruited
to the sample group
provides multiple
referrals.
Exponential discriminative
snowball sampling
Subjects give multiple
referrals, however, only
one new subject is
recruited among them.
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Linear snowball sampling
Formation of a sample
group starts with only one
subject and the subject
provides only one referral.

31. Advantages
The ability to recruit hidden
populations
The possibility to collect
primary data in low cost
It can be completed in a short
duration of time
A very little planning is required
to start sampling process
PRONS & CONS
Disadvantages
Oversampling can be done
Respondents may be hesitant
to ask all questions
It is not possible to determine
the actual pattern of
distribution of population.
It is not possible to determine
the sampling error 31

32. REFERENCES
https://research-methodology.net
http://www.statisticshowto.com
https://images.google.com/
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