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 & Dietetics School of Nutrition & Dietetics

Faculty of Health SciencesFaculty of Health Sciences

UniversitiUniversiti Sultan Sultan ZainalZainal AbidinAbidin

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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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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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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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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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Theory of causality and research design

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•

•

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• Cannot be eliminated. • Possible to quantify

the impact of extraneous variables on dependent variable

• CONTROL GROUP

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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Change Change because of because of

independent independent variablevariable

Change Change because of because of extraneous extraneous

variablevariable

Change Change because of because of

chancechance

Change in Change in dependent dependent

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

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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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.

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.

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

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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Thank YouThank You

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