Lecture 2-Variables & Lit review - definitions, classification and sources of literature pptx

Variables
&
Literature review
5th
Year, 2025
Department of Community Medicine
School of Medicine
University of Juba
Kon P. Alier, B.Pharm (Hons), MPH

Learning objectives
 Understanding variables
– Definition
– classification
– Sources of literature
– Measurement scales
 Literature review
– Define literature
– Sources of literature
– Literature review process

Defining variables…(1)
 A variable is a characteristic (of a person, object or
phenomenon) that can take on different values
 An image, perception or concept capable of
measurement is a variable
 It may change (as opposed to constants) in the
same person at different times or it varies from
person to person at the same time
 It is the data needed to meet the objectives of the
study

Defining variables…(2)
 Examples:
 Colour
 Age
 Weight
 Attitudes
 Knowledge
 Practices
 Income
 Location
 Bed capacity
 Number of staff
 Bed occupancy
 Waiting time
 Availability of drugs
 Frequency of supervision

Difference between variable and concept (1)
 A concept is simply a mental image which cannot be
measured
 Measurability is the key difference between the two
(concept and variable)

 A concept may be converted into a variable through
operationalization- identifying indicators for the
concept e.g. richness may become a variable
through identifying the ingredients such as assets
(house, cars, …) these items have monetary values
which vary

 Operationalization consists of three elements:
 Selection of indicators which reflect the presence
/absence of an element e.g. literacy: (reading speed,
comprehension, readers’ response, etc.)
 Quantification of indicators; assigning scores that
represent the presence or absence of a value e.g. The
normal reading speed should be 100 letters per minute
 Quantification of the variable; identification of values
that the variables can assume e.g a child who cannot
read 100 letters in a minute is considered illiterate and
vice versa.

Classification of variables… (1)
 Three criteria are used:
 Causal relationship;
 Study design;
 Unit of measurement.

 Under causal relationship:
 Change (independent) variables; which are responsible
for bringing about change in a phenomenon, situation or
circumstance;
 Outcome (dependent) variables; which are the effects,
impacts or consequences of a change variable;
 (Extraneous) variables which affect or influence the link
between cause-and-effect variables;
 Connecting or linking (intervening) variables; which in
certain situations are necessary to complete the
relationship
 Extraneous & intervening variables are known as
confounding variables

 Under study design:
 Active variable; can be manipulated, changed or
controlled e.g. programs, teaching models
 Attribute variable; cannot be manipulated, changed or
controlled, and reflect the characteristics of the study
population, for example age, gender, education and
income.

 Under measurement:
 Categorical scale includes:
 Constant variable e.g. tree, lorry, cow
 Dichotomous variables e.g. yes/no, male/female
 Polytomous variables; divided into more than two categories
e.g. religion (Islam, Christianity, Buddhism etc.)
 Continuous variables; age, weight

Measurement scales
 Four categories are used (Stevens, 1978)
 Nominal or classificatory scale; a common characteristic is
used to identify groups or subgroups
 Ordinal or ranking scale; groups are ranked into some order
 Interval scale: Helps us to measure the distance between two
values and contains equal intervals. It uses a unit measurement
that enables responses to be divided into equally spaced
units/intervals. Expressed in units that have absolute value &
remain constant. e.g. the IQ of 3 students is 100, 150 & 200
respectively.
 In nominal terms, the 3 have different IQs.
 In ordinal terms, the1st has a lower, 2nd has high & 3rd has higher IQ.
 In interval terms, IQ of 2nd student is 50 points higher than the 1st
one, while 3rd student’s IQ is 100 points higher than 1st student.
 Ratio scale: measures proportions and ratios

Ensuring Quality of Measurement
 Measuring particular attributes among people
should reflect “true” differences on that attribute.
 Which criteria do we use to evaluate the quality of
our measurement?
 Through testing for reliability & validity.
 Reliability – a good measure is one that is consistent
(repeated with comparable results).
 Validity - a good measure must be accurate and
measures only what it is supposed to measure e.g. if the
aim is to find out about “health needs” but instrument
finds out “attitudes of respondents to health needs”,
then it is not valid.

Criterion of Reliability
 Test – Retest method
 Making the same measurement more than once under
similar conditions.
 Tests external consistency.
 Split – half method
 Divide the group into two equal parts & administer the
same questionnaire or test.
 Tests internal consistency.

Criterion of validity
 Face or Content validity
 It is about judging the degree to which the measuring
strategy is adequate in the face of researchers or their
critics.
 Does it cover all the possible aspects or variables of the
research topic?
 Judged on the basis of the extent to which statements or
questions they are supposed to measure as judged by
the researcher & experts in the field of study.
 Does the empirical measure conform to our common
agreement?
 Based upon subjective logic

Exercise
Suppose you are a County Health Director and you
believe that anaemia, malaria and malnutrition are
serious problems in your county, especially among
adult male farmers… and you wish to study the
prevalence of the problems in adult males of different
ages, occupations and education.
 What are your
 Independent Variables?
 Dependent Variables?
 Construct a conceptual framework for your variables

What is Literature?
• All the published work on a particular subject,
irrespective of the quality
• Literature review
– an independent written work that gives a concise
summary of previous findings in the literature on a
given subject
– Should have:
• References showing reviewed documents
• References should be read, may require page
numbers
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Sources of literature... (1)
• Published:
• Libraries
• Text Books
• Journals and other publications
• Reports of Departments or other organizational studies
• Conference proceedings
• Theses and dissertations
• The Internet
• Other electronic storage media (Diskettes, CDs etc)
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Sources of literature... (2)
• Unpublished:
• Government offices: MOH, MOFPED, states, counties
• Health units
• NGOs (local and international)
• Newspapers
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Why review literature?... (1)
• Prevents duplication of what has already been
done
• Helps to find what others have already learnt
(helps to refine your problem statement)
• Helps to know the methodologies used in your
type of study
• Helps to concretize your arguments why your
research should be done
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Why review literature?... (2)
• Helps to identify and anticipate problems that
may be encountered during study and their
possible solutions
• Reveals commonalities and inconsistencies in
studies
• Identifies gaps for further research
• Helps you to adopt a particular type of design
• Construction of tools
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Literature review process… (1)
• Searching
• From many sources
• The first step is to get as much literature as possible on the
topic or objectives of study
• Assessing
• Whether the literature available is reliable or just misleading
• Integrating
• Critiquing the methodologies- sample size, sampling
procedure etc
• Comment on the findings of others – globally, locally
• What have others concluded or recommended
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Literature review process… (2)
• The key focus is on review as well as literature:
• What is known about the topic?
• Why is this an important topic?
• What is unknown?
• Why are some things unknown? (speculate)
• Why should the gaps be filled?
• Which gaps do you propose to fill & why have you chosen
them?
• How do you propose to fill them?
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Guidelines for literature review… (1)
1. Support every claim with evidence
2. Be selective (all materials selected must relate
directly to the topic)
3. Use quote sparingly there is no space for long and
frequent quotes
4. Summarize and synthesize (recapitulate what the
author says and synthesize it by rephrasing the
study’s significance and relating it to your work)
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Guidelines for literature review… (2)
5. Keep your own voice
– Although literature review represents others ideas , the
reviewer should remain at the center The reviewer should
simply weave references to other sources. While the
literature review presents others peoples’ ideas, the
reviewer’s voice (the writer’s) should remain front and at
the center..
6. Use caution when paraphrasing:
– Be sure to represent the author’s information or opinion
accurately
7. Use your own words.
– To avoid plagiarism, in your work, indicate with quotation
marks whenever the ideas/words used are not your own.
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