Sampling in research

1. Population is the entire group
of people, organisms or things
that share similar features and
characteristics which are of high
relevance to the research being
conducted. In an action research
being conducted in a particular
school, all students can be
considered the population.

2. • Sample refers to members of a certain population.
A sample is a representation of the entire
population carrying the same characteristics. Taking
the enrolled learners in a particular school as
population, two sections or classes in that school
may serve as sample. The process of selecting the
samples is called sampling.
• Sampling Technique pertains to the specific
manner or ways of selecting the sample which are
discussed in your previous classes in Research and
Mathematics. In quantitative research, sampling
may require statistical operations, to ensure that
the number of participants is sufficient to collect
the data needed; while in qualitative research,
selecting the specific number of samples has no
definite rules. However, the consideration should
be ensured in terms of saturation of the data about
the topic and the variation that is needed within
the target population.

3. Question:
•How will you know if the person you are
asking is best suited as a sample in
your research?

4. • At the end of this module, you should be
able to:
• Cognitive:
1. Determine the different sampling techniques
2. Choose the technique compliment the research being studie
• Affective:
1. Appreciate the importance of different sampling techniques
• Psychomotor:
1. Write the methodology section of one’s research study;

5. Sampling Techniques
• The primary purpose of sampling is the selection of suitable
participants to enable the focus of the study to be appropriately
researched. As with all types of research, effective sample selection is a
vital part of the research design process. Inappropriate sampling
approaches may seriously affect the findings and outcomes of a
study. There are a number of types of sampling procedures that can be
adopted and the choice of the qualitative research design will often
guide that process.

7. Probability Sampling
A. Random Sampling-is a process whose
members had an equal chance of being
selected from the population .
1.Simple Random- is a process of
selecting n sample via random number or
lottery.
2.Systematic Sampling- is a process of
selecting every 2nd ,3rd ect. of a population

8. 3. Stratified Sampling
-is a process of subdividing the population
into sub group and drawing members at
random from each subgroup or stratum.
𝑛 =
𝑡𝑜𝑡𝑎𝑙 𝑛𝑜. 𝑜𝑓 𝑔𝑟𝑜𝑢𝑝
𝑡𝑜𝑡𝑎𝑙 𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛
𝑥 100
POPULATION
STEM -53
ABM-34
HUMSS -110
TVL -78________
275
Sample
size =96

9. 4. Cluster sampling-is a process of
selecting cluster from a population or
widely spread out over a wide
geographical area.

10. NON PROBABILITY
Sampling in qualitative research is termed non-
probability sampling. Unlike probability sampling used in
quantitative research, non-probability sampling does not
involve randomization. This means that members of a
qualitative study population do not have an equal chance of
being selected. Instead, they are often ‘specifically’ picked by
the researchers. Whitehead and Whitehead (2016) identified
four main types of sampling of non-probability sampling, as
follows:

12. 1. Convenience Sampling
• This is the most common form of qualitative sampling, and it occurs
when people are invited to participate in the study because they are
conveniently (opportunistically) available with regard to access, location,
time, and willingness. Convenience sampling is a relatively fast and easy
way to achieve the sample size needed for the study.
• While it may be the most common form of sampling in qualitative research,
the main limitation of using convenience sampling is that it could suffer from
either under-representation or over-representation of particular groups within
the population.

14. 2. Purposive Sampling
Purposive sampling is a popular approach in qualitative
research. Participants are recruited according to pre-selected
criteria relevant to the research aims/questions of a given study.
Purposive sampling is designed to provide information-rich
cases as participants are those who have the required
status, experience, or knowledge of interest to the
researcher.

16. 3. Snowball Sampling
• Also known as ‘chain referral’ or ‘networking’ sampling,
snowball sampling occurs when the researcher starts gathering
information from one or a small number of people and then requests
to put the researcher in touch with others who may be friends,
relatives, colleagues, or other significant contacts. This type of
sampling is especially useful in recruiting ‘hidden populations’, for
example, marginalized or stigmatized individuals, where those individuals
are not easily accessible to researchers, such as drug-users, prostitutes,
or those not registered with a medical practice (Babbie 2014).

17. •Some limitations of snowball sampling
are that the researcher needs to rely on
referrals from initial contacts to generate
additional participants. The participants,
therefore, are often not considered to be
representative of the overall population
being studied.

19. 4. Theoretical Sampling
• This form of sampling is mostly used in grounded theory studies but
is increasingly being used to gather data for the purpose of theory
generation. The research starts from a homogeneous (small) sample
and moves to a heterogeneous (larger) sample (Babbie 2014). Sampling
occurs sequentially and alongside data analysis. Analyzed data guides the
areas to be explored further in the next round of data collection and the focus
of the sample in order to achieve this. The initial participants are usually
purposively chosen or conveniently available.

20. Synthesis
• It is possible however, to use more than one form of
sampling in a single study. For example, in a study by
Zhou (2014), purposive sampling was initially used to
select participants. When categories were tentatively
established, theoretical sampling was then employed.

21. • Learning Task 4: On your notebook, decide about
the population, sample and the sampling technique
that you are going to use in your research work.
• A. Population :
_______________________________________
• B. Sample :
_______________________________________
• C. Sampling Technique :
_______________________________________

22. •Bibliography
• Melegrito L. and Mendoza D. Applied Research: Introduction to Quantitative Research Method and
Report Writing. Phoenix Publishing House 2016
• Fraenbel, J. Wallen, N., and Hyun, H. 2012. How to design and evaluate research in education. 2012.
USA: Mc-Graw-Hill.
• Creswell, J. 2014. Research design: qualitative, quantitative, and mixed method approaches. 4th ed.
Los Angeles: Sage.
• Jesson, J., Matheson, L., and Lacy, F. 2011. Doing your literature review: Traditional and systematic
techniques. Los Angeles: Sage.
• Baraceros E. Practical Research 2. Rex Publishing House 2016