1. KNOWLEDGE FOR THE BENEFIT OF HUMANITYKNOWLEDGE FOR THE BENEFIT OF HUMANITY
RESEARCH METHODOLOGY (HFS4343)
SELECTING A STUDY DESIGN
Dr.Dr. MohdMohd RazifRazif ShahrilShahril
School of Nutrition & DieteticsSchool of Nutrition & Dietetics
Faculty of Health SciencesFaculty of Health Sciences
UniversitiUniversiti SultanSultan ZainalZainal AbidinAbidin
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2. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Topic Learning Outcomes
At the end of this lecture, students should be able to;
• define what research design means
• identify the important functions of research design
• explain the theory of causality and the research design
• explain the differences between quantitative and
qualitative study designs
• identify common study designs in quantitative and
qualitative research and when to use them
• explain the strengths and weaknesses of different study
designs
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3. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
What is research design?
• A plan, structure and strategy of investigation so
conceived as to obtain answers to research questions or
problems.
– the complete scheme or programme of the research.
– includes an outline of what the investigator will do
from writing the hypotheses and their operational
implications to the final analysis of data.
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4. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Functions of a research design
• Conceptualise an operational plan to undertake the
various procedures and tasks required to complete the
study
• Ensure that these procedures are adequate to obtain
valid, objective and accurate answers to the research
questions – control of variance
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5. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Theory of causality and research design
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6. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Theory of causality and research design
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•
•
•
• Cannot be eliminated.
• Possible to quantify
the impact of
extraneous variables
on dependent variable
• CONTROL GROUP

7. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Theory of causality and research design
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ChangeChange
because ofbecause of
independentindependent
variablevariable
ChangeChange
because ofbecause of
extraneousextraneous
variablevariable
ChangeChange
because ofbecause of
chancechance
Change inChange in
dependentdependent
variablevariable
• As the total change measures the combined effect of all
three components it is difficult to isolate the individual
impact of each of them.
• We need to design our study to ensure that the
independent variable has the maximum opportunity to
have its full effect on the dependent variable
– the effects that are attributed to extraneous and chance variables
are minimised (if possible) or quantified or eliminated

8. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
How to minimise effect of extraneous
variables?
• Ensure that extraneous variables have a similar
impact on control and experimental groups.
– Randomisation
– Matching
• Eliminate extraneous variable(s).
– Build the affecting variable into the design of the study
– Eliminate the variable
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9. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Quantitative vs. qualitative study design
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QUANTITATIVE STUDY DESIGN QUALITATIVE STUDY DESIGN
Designs are specific, well structured,
have been tested for their validity and
reliability, and can be explicitly defined
and recognised.
Designs are less specific and precise,
and do not have the same structural
depth.
Designs are often based on inductive
logic, are more structured, rigid, fixed
and predetermined in their use to
ensure accuracy in measurement and
classification.
Designs are often based on deductive
logic, are flexible and emergent in
nature, and are often non-linear and
non-sequential in their
operationalisation
Have more clarity and distinction
between designs and methods of data
collection.
Distinction between study designs and
methods of data collection is far less
clear.

10. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Quantitative vs. qualitative study design (cont.)
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QUANTITATIVE STUDY DESIGN QUALITATIVE STUDY DESIGN
Respondent concordance does not
occupy an important place. Sometimes
it is assumed to be achieved by
circulating or sharing the findings with
those who participated in the study.
The adherence to the concept of
respondent concordance whereby you
as a researcher make every effort to
seek agreement of your respondents
with your interpretation, presentation
of the situations, experiences,
perceptions and conclusions.
Enough detail about a study design is
provided for it to be replicated for
verification and reassurance
Little attention is paid to study designs
or the other structural aspects of a
study, hence the replication of a study
design becomes almost impossible.

11. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Quantitative vs. qualitative study design (cont.)
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QUANTITATIVE STUDY DESIGN QUALITATIVE STUDY DESIGN
Low possibility of introducing
researcher bias.
High possibility of introducing
researcher bias
More suited to finding out the extent of
variation and diversity.
More appropriate for exploring the
variation and diversity in any aspect of
social life

12. S C H O O L O F N U T R I T I O N A N D D I E T E T I C S • U N I V E R S I T I S U L T A N Z A I N A L A B I D I N
Types of study design
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13. Thank YouThank You
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