There are four issues to consider when deciding whether to use probability or nonprobability sampling:

1. 
10/14/2022
Types of Sampling Procedures
Probability Sampling Non-Probability Sampling
Probability
sampling uses
mathematical
guidelines whereby
each unit’s chance
for selection is
known.
Non-probability
sampling does not
follow the
guidelines of
mathematical
probability.
Muhammad Awais
(facebook.com/awwaiis)

2. 
 There are four issues to consider when deciding
whether to use probability or nonprobability
sampling:
 Purpose of the study.
 Some studies are not designed to generalize the results
to the population but rather to investigate variable
relationships or collect exploratory data to design
questionnaires or measurement instruments.
Nonprobability sampling is appropriate in these
situations.
10/14/2022
Factors to determine Sampling
Techniques
Muhammad Awais
(facebook.com/awwaiis)

3. 
 Cost versus value.
 A sample should produce the greatest value for the
least investment. If the cost of probability sampling is
too high in relation to the type and quality of
information collected or the purpose of the study, then
nonprobability sampling is usually satisfactory.
 Time constraints.
 In many cases researchers collecting preliminary
information operate under time constraints imposed
by sponsoring agencies, management directives, or
publication guidelines. Since probability sampling is
often time consuming, a nonprobability sample may
meet the need temporarily
10/14/2022
Muhammad Awais
(facebook.com/awwaiis)

4. 
 Amount of acceptable error.
 In preliminary studies or pilot studies, where error
control is not a prime concern, a nonprobability
sample is usually adequate.
10/14/2022
Muhammad Awais
(facebook.com/awwaiis)

5. 
 Researchers in the behavioral sciences can only invite
respondents or subjects to participate in a research
project; they cannot force them to answer questions
or participate in a research study (nor can
researchers force a person to stay involved in a
research project until its conclusion). However, there
is a significant difference in how such respondents/
subjects get into a sample.
10/14/2022
Muhammad Awais
(facebook.com/awwaiis)

6. 
 In one case, there are no qualifications or restrictions related to who
gets into a sample (known as screener questions in survey design).
This type of sample is a totally self-selected, nonprobability sample
that we label an unqualified volunteer sample.
 In the second case, probability sampling is followed and the sample
consists of systematically selected respondents whose names were
chosen using some probability method. These people must qualify
(pass) on one or more questions to be eligible for the sample, such as
age, sex, use of the media, and so on. However, even respondents in
this type of sample must volunteer to participate in a research
kproject—they cannot be forced to participate. We label this a
qualified volunteer sample.
10/14/2022
Muhammad Awais
(facebook.com/awwaiis)