Non-probability and its types

1. Non Probability and its Types

2. Non probability sample
Definition
Non-probability sampling is a sampling technique
where the samples are gathered in a process that does not give
all the individuals in the population equal chances of being
selected.
The difference between nonprobability and probability sampling
is that nonprobability sampling does not involve random
selection and probability sampling does.

3. Types of Non Probability
Convenience sampling
Judgment sampling
Quota sampling

4. Convenience Sampling
Convenience sampling is a non-probability sampling
technique where subjects are selected because of their
convenient accessibility and proximity to the
researcher.

5. Example
Samples those are familiar to the researcher like :
Friends, Co-workers, that is easily accessible to the
researcher.

6. Advantages & Disadvantages
Advantages
• Saves time, money and
effort.
• Easy data collection through
a known group or class.
Disadvantages
• No accurate way to assess
representativeness of
samples.
• Possible restrictions of
generalization about the
study findings.

7. Judgment Sampling
Judgmental sampling is a non-probability sampling
technique where the researcher selects units to be
sampled based on their knowledge and professional
judgment.

8. Example
Suppose 100 boys are to be selected from a college with 1000
boys. If nothing is known about the students in this college, then
the investigator may visit the college and choose the first 100
boys he meets. Or he may select 100 boys all belonging to 3rd
Year. Or he might select 25 boys from Commerce course, 25 from
Science courses, 25 boys from Arts courses and 25 from Fine arts
courses.
Hence, when only the sample size is known, the investigator uses
his judgment and select the sample.

9. Advantages & Disadvantages
Advantages
• Samples are chosen well,
based on a certain criterion.
• There is assurance of quality
responses.
Disadvantages
• Unfairly selection of samples
may occur.
• Time-consuming process.

10. Quota Sampling
In this method, the sample size is determined first and
then quota is fixed for various categories of population,
which is followed while selecting the sample.

11. Example
Suppose we want to select 100 students, then we might say that
the sample should be according to the quota given below :
Boys 50%, Girls 50% Then among the boys, 60% college students,
30% high school students and 10% elementary school students.
A different or the same quota may be fixed for the girls.

12. Advantages & Disadvantages
Advantages
• Useful when the research
budget is very tight.
Disadvantages
• The result might be at risk
that the sample would not
be typical of the desired
sample quality.

13. THE END
Thanks for paying attention…