Introduction to Research Methodology

1. EPIDEMIOLOGICAL
STUDIES
By
A.P. Kulkarni

2. WHAT IS RESEARCH?
 Research produces findings that are not
determined in advance.
 Produce findings that are applicable beyond the
immediate boundaries of the study. (External
validation)
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3. WHAT IS RESEARCH?
 Seeks answer to a question. This is the RQ.
Uncertainty that researcher wants to clear. It is also
a knowledge gap that the researcher wants to fill.
 Systematically uses a predefined set of procedures
to answer the question. Study design that the
researcher uses and material and methods that are
explained therein.
 Collects evidence: In the form of data, variables
and statistics. (Descriptive or inferential)
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4. RESEARCH QUESTION
Question that epidemiologist is seeking
answer to
RQ1: What is prevalence of diabetes in
allopathic doctors in Maharashtra?
Good RQ:
Variable: Prevalence of diabetes
Population: (Participants) Allopathic
doctors in Maharashtra

5. RESEARCH QUESTION
Question that epidemiologist is seeking
answer to
RQ2: What is the average daily intake of
proteins and calories in male and female
students of PIMS DU?
Variable: i. Average daily intake of proteins
ii. Average daily intake of calories
Population: (Participants) i. Male students
of PIMS DU, ii) Female students of PIMS
DU

6. VARIABLES
PRIMARY VARIABLES:
 Variables in RQ
 Prevalence of diabetes in RQ1, Average
daily intake of Calories and proteins in
RQ2
SECONDARY VARIABLES
 Variables in NOT in RQ, but in study
 Eg. Gender, Years of practice, Specialty,
Residence (R/U) in RQ1

7. TYPES OF RQ
Type of RQ
Based on aim
Descriptive
Correlation
Association
Difference
Based on number
of variables
Simple
Complex

8. DESCRIPTIVE TYPE OF RQ
Seek for
Description of disease
Person distribution
Place distribution
Time distribution
Estimate of
Prevalence,
incidence,
mean

9. DESCRIBE DISEASE
RQ3: What is the profile of anemia in ANCs
attending GMC, Aurangabad?
Profile: Age, SE status, Parity, Birth
interval, BOH
Note: Persons distribution, one group
RQ4: What is the performance of MBBS
students in different colleges of MUHS in
PSM in 2016 winter exams?
Note : Place distribution, one group

10. SEEKING FOR ESTIMATES
RQ1: What is prevalence of diabetes in
allopathic doctors in Maharashtra?
Note: Seeking for prevalence
RQ2: What is the average daily intake of
proteins and calories in male and female
students of GMC, Aurangabad?
Note: Seeking for average

11. ASSOCIATION TYPE OF RQ
Seek to
establish
Correlation

12. SEEKING TO ESTABLISH CORRELATION
Correlation: Mathematical relationship
between two or more quantitative
variables (Variable expressed in number)
Dependent (Outcome) variable
Independent variables
RQ7: Is there a correlation between birth
weight of newborn and
i) MAC, ii) CC, and iii) HC of the newborn
Note: >1 independent variables
One group

13. ASSOCIATION TYPE OF RQ
Seek to
establish
Association

14. ASSOCIATION
Relationship of one qualitative variable
with one or more qualitative variables
 Disease or health related event is the one
of interest and is called OUTCOME or
Dependent variable
 Other variables with which association of
outcome is to be tested are called RISK
FACTORS or Independent variables

15. SEEKING TO ESTABLISH ASSOCIATION
RQ5: Is there an association between
Satisfactory attendance and Passing in
Community Medicine Internal
Examinations in MBBS students of
college-X?
Outcome (Dependent) variable: Passing
Independent variable: Attendance
Note: One outcome and one independent
variable each
Requires information from at least 2 groups

16. SEEKING TO ESTABLISH
ASSOCIATION
RQ6: Is there an association between acute
pancreatitis and smoking and type-1
diabetes
Outcome (Dependent) variable: Acute
pancreatitis
Independent variable: Smoking & type-
1 diabetes
Note: One outcome and TWO independent
variables, requires info from at least 2
groups

17. DIFFERENCE TYPE OF RQ
Seeks to find if there is a difference in the
variable in two or more groups
 If so, difference in profile of two groups
is the probable reason for difference in
variable?

18. DIFFERENCE TYPE OF RQ
Difference of a variable in 2 or more
groups
RQ8: Is there a difference in the mean Hb%
of boys and girls of GMC, Aurangabad?
(Implied inference: If so, gender difference
is probable reason of difference in Hb%)
Dependent (Outcome): Hb%
Independent: Gender
Note: 2 groups

19. DIFFERENCE TYPE OF RQ
Difference of a variable in 2 or more
groups
RQ8: Is there a difference in the mean Hb%
of boys and girls of RMC Loni?
(Implied inference: If so, gender difference
is probable reason of difference in Hb%)
Dependent (Outcome): Hb%
Independent: Gender
Note: 2 groups

20. DIFFERENCE TYPE OF RQ
RQ9: Is the persistence rate of S. typhi in
blood of typhoid patients, one week after
completion of treatment is lesser with
Ciprofloxacin than with chloramphenicol?
Dependent (Outcome): Persistence rate
Independent: Treatment given
Note: 2 groups

21. WHY KNOW TYPE OF RQ?
Decides type of study required to get answer
Type of RQ Groups Type of study
Descriptive 1 Descriptive
Correlation 1 Descriptive
Association 2 Analytical ,
Experimental
Difference 2 Analytical ,
Experimental

22. HYPOTHESISESIS
 It is a testable prediction about relationship between
variables.
 Based on previous experience.
 With the study, investigator tries to find if supposition
is true or not.
 Integral part of ANALYTICAL and EXPERIMENTAL
studies
 Not required in DESCRIPTIVE studies. (Hypothesis
generating study)
 Constructed from research question
ResearchMethodology

23. ELEMENTS OF HYPOTHESIS
1. Population
2. Suspected cause/s (Independent variable/s)
3. Expected out-come (Dependent variable)
4. Dose response relationship (if any)
5. Time response relationship (if any)
6. Direction of relationship
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24. • Hypothesis:-1: There is difference
in daily calorie intake between male
& female medical students of
Maharashtra?
RQ-1: What is the
difference in daily
calorie intake between
male & female medical
students of
Maharashtra?
• Hypothesis-2: There is positive
relationship between birth weight
and length, MAC, CC and HCHC of
newborn born in hospital-X
Q-2: What is the
relationship between
birth weight and length,
MAC, CC and HC of
newborn born in
hospital-X ?
• When direction of relationship is
included in hypothesis
• Example: Hypothesis-2
Directional
hypothesis
• When direction of relationship is NOT
included in hypothesis
• Example: Hypothesis-1
Non-directional
hypothesis
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25. • Only one dependent & independent
variable
Simple Hypothesis
• Many dependent/ independent
variables
Complex
Hypothesis
• Increase in 1 cm of height adds 1 kg
in weight of adults
Dose-response
relationship
• Other side of coin
• Hypothesis stating that no
difference/ association/ relation exist
exist
Null Hypothesis
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26. TYPES OF HYPOTHESIS
1. Simple/ Complex
2. Directional / Non-directional
3. Null/ Research
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27. SELECTION OF TOPIC: FINER CRITERIA
Feasibility
• Technical
• Operational
• Administrative
Interesting
• Ability to spare time
• Intellectual challenge
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28. SELECTION OF TOPIC: FINER CRITERIA
Novelty
• Reduction in cost
• Improved safety
• Reduction in duration of
treatment
• Reduction in duration of
hospital stay
• Better acceptability
• Filling gaps in knowledge
• Confirming or refuting earlier
observations
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29. SELECTION OF TOPIC: FINER CRITERIA
Ethical
aspects
• Not causing danger to human
beings
• No exploitation
• Not imposing additional coast
(Compensation/ insurance)
• Not against beliefs/ customs
• Informed consent
• Ethics committee approval
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30. SELECTION OF TOPIC: FINER CRITERIA
Relevance
• Relevance : Local /
Regional / National
•Addressing problem of
importance
• Making life easier ?
• Against National Health
Policy?
• Relative term ?
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31. Study type
Observational
Descriptive
Cross
sectional
Longitudinal
Analytical
Case-control Cohort
Analytical
cross
sectional
Experimental
Meta-analysis
Case study
Case series
Cross sectional