Research methodology 2

GD MRN
www.indiandentalacade
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22/03/06
……..In Search of Research..In Search of Researchwww.indiandentalacademy.com

Contents :
► Overview of research
► Types of research
► Health research
► Scientific foundation of research
► Research strategies and design
► Descriptive studies
► Analytical studies
● Case control studies
● Cohort studies
► Experimental studies
● Clinical trials
● Field trials
► Construction of research design
► Ethical considerations
► Conclusion
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What is research?
Research is the method of science. It is a
systematic body of procedures & techniques
applied in carrying out investigation or
experimentation targeted at obtaining new
knowledge.
Research is a quest for knowledge throughResearch is a quest for knowledge through
diligent search or investigation ordiligent search or investigation or
experimentation aimed at the discovery &experimentation aimed at the discovery &
interpretation of new knowledgeinterpretation of new knowledgewww.indiandentalacade
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Categories of research
1. Empirical & Theoretical research
a) Empirical research – It is done based on
observation & experience. It involves measurem
of variables, estimation of population parameters
statistical analysis
b) Theoretical research – It is done based on
theory & abstraction. It involves more of
imagination & application of mathematical
abstractions
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Categories of research
2. Basic & Applied research
a) Basic research – It involves a
search for knowledge without a
defined goal of utility or specific
purpose. e.g. Laws of motion by Sir
Isaac Newton
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b) Applied research –
It is problem oriented &
directed toward a defined &
purposeful end. It is
frequently generated by a
perceived need & is
directed toward the solution
of an existing problem. e.g.
Application of Laws of
motion in designing a rocket
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Health research
All the research in the field of health may be
basic or applied, empirical or theoretical is
classified under three operationally
interlinking categories.
1. Bio-medical research
2. Behavioral research
3. Health services research
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Bio-medical research
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Behavioral research
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Health services research
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Health research triangle
This illustration shows the intercommunication
between the three categories of health research
Bio-medical Behavioral
Health services
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Scientific foundations of research
1) Order
2) Inference & chance
3) Maintenance of probability
4) Hypotheses
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Order :
Research employs an organized
observation of entities or events
which are classified or ordered on
the basis of common properties &
behaviors. The commonality among
the observations help in predictions
which carry to the ultimate become
laws.
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Inference & chance:
Reasoning or inference is the force of advance in
research. There are two distinct approaches in
the development of inferences
• DEDUCTIVE – It moves from the general to the
specific. Hence it does not allow for the element
of chance. It is not used much in health research.
• INDUCTIVE – It moves from specific to the
general. There is extrapolation of results from a
sample to the target population. Health research
depends almost entirely upon inductive
reasoning. Hence chance must be fully accounted
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Maintenance of probability:
Maintaining a very high probability & eliminating
the chance occurrence is critical to ensure the
validity of a research.
Techniques used to maintain high probability
1. Representative sampling
2. Randomization in selection of study groups
3. Maintenance of comparison groups as
controls
4. Blinding procedures
5. Statistical methods
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Hypothesis:
Hypothesis is defined as a presumption,
supposition or assumption derived either out
of observation or reflection.
Hypotheses are carefully constructed
statements generated from inferences & they
use argument of induction.
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OBSERVATIONAL
DESCRIPTIVE
ANALYTIC
COHORT
STUDIES
CASE CONTROL
STUDIES
INSTITUTIONAL
SURVEYS
COMMUNITY
SURVEYS
APPROACH DESIGN
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EXPERIMENTAL ANALYTICAL
TRIALS
LABORATORY
EXPERIMENTS
APPROACH DESIGN
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BASIC ELEMENTS OF STUDY DESIGN
A) CONCEPTUALIZING THE PROBLEM
Need
Background
Rationale
B) FORMULATING THE OBJECTIVES
Generating hypotheses
Testing hypotheses
C) DESIGNING THE APPROACH
Research design
Strategic pathways
Methods and materials
D) DEFINING THE POPULATION
Target population
Study population
E) DEFINING THE MEASUREMENTS
Methods of collection
Precision, accuracy, reliability. F) ANALYSIS & INTERPRETATION
OF RESULTS
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Research design :
►Strategies include…
● Definition of variables
● Their level
● Relationship to one another
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Classification of studies
•Descriptive study
•Analytical study
Cross sectional studyCross sectional study
Case control studyCase control study
Cohort- follow upCohort- follow up
Observational study Experimental study
•Randomised control trials/
clinical trials
• field trial/ community
intervention trial
•Community trial
All these study complement each other
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22/03/06
Descriptive StudyDescriptive Study
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Descriptive study
►Def … when a study is not
structured formally as an
etiological hypothesis;
►Allows…formulation of hypothesis…
►1st
phase of an investigation
They ask the question
● When…time dist
● Where…place dist
● Who… person dist
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►Procedure in descriptive study
● Defining pop to b studied
● Defining disease under stud
● Desc…dis by time, person n place
● Measurement of disease
● Comparing with known indices
● Formulation of etiological
hypothesis
Descriptive study
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►Def the population
● Age , sex, occupation, culture,
characteristics n similar infor
● Pop shd b large enough
● Stable of migration
● No visitors n relative
Provide denominator for calculating
rates, measurement of frequency,
distribution n determination of disease
Descriptive study
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►Def the disease under study
● Precise n valid
● Operational def…. Identified n
measured
►Describing the disease
● Time distribution…time, place , person
● Time trends or fluctuations
 Short term fluctuation
 Periodic fluctuation
 Long term fluctuation
Descriptive study
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● Place distribution – b/w countries
 Genes Vs environment
 Role of diet
 Migration changes
 Geographic variations
● Person distribution – natural hist of
dis.
Descriptive study
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►Measurement of disease :
● Mortality-
● Morbidity-
 incidence – longitudinal stud.
 prevelance - cross sectional stud.
● Disability
►Comparing with known indices
Descriptive study
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►Formulation of hypothesis
►Should specify :
● The population
● Specific cause
● Expected outcome
● Dose response relationship
● Time response relationship
►E.g. ‘cigarette smoking causes lung cancer’ –
incomplete
►‘the smoking of 30-40 cig/day causes lung
cancer in 10% of smokers after 20 yrs of
exposure’
Descriptive study
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►Uses :
● Data regarding magnitude
● Clues – dis. Etiology
● Background data – P, O & E
● Des variation in dis occurrence
Descriptive study
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Analytical StudyAnalytical Study

Analytical studies
►Interest – individual…
►Test a hypothesis
● Det. Stat assosiation
● Strength of assosiation
►2 types :
● Case control study
● Cohort study
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22/03/06
Case-Control Studies

Case-control study design
Exposure Disease Observer
?
Choose groups with and without disease,
look back at what different exposures
they may have had
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Case control studies
►Attempt to make inference from existing
observations (retrospective)
►Compares patients with outcome/disease
with those without and attempts to
identify factors that influenced that
outcome (or caused that disease)
►Important concept: start with the
result (disease) and work backwards
for the cause
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►Basic steps :
● Selection of cases & controls
● Matching
● Measurement of exposure
● Analysis & interpretation
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Strengths of case-control
design
►Best study when have rare disease
or outcome
►Relatively quick and inexpensive
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Weaknesses (potential
biases)
►Selection (confounding) bias: controls
must be as similar to cases as possible
►Berkinsonian bias…
►Recall bias: cases may be able to
remember events better because of its
significance or may be prompted to
remember by investigators
►Survival bias: dead people don’t make it
into many case-cohort studies; and if they
do, they don’t remember things very well
►Interviewer’s bias
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Ways to combat weakness
►Matching: for each case, find a
control that looks just like him/her
in all other possible ways except for
the disease (same age, race,
economic class, etc.)
►Blinding: individual assessing
exposures should be blinded to
whether the person is a case or
control
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Cohort Studies/Prospective
study/ Longitudinal/
Incidence/Forward-looking study

Cohort studies
►Studies whether exposure to a “risk
factor” is associated with a subsequent
“outcome”
►Select two populations who seem the
same except for the hypothesized risk
factor
►Follow them and see how many have the
outcome or disease
►Important concept: Start with the risk,
then look for the outcome
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►Consideration in assembling cohorts
● Free of disease
● Equally susceptible to disease
● Comparable groups
● Diagnostic n eligibility criteria
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Cohort study design
(Prospective)
Exposure Observer Disease
?
Start with two groups of people who are
exposed and unexposed, follow them to
see who gets disease.
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Cohort study design
(Retrospective/Historical)
Exposure Disease Observer
?
Start with two groups of people who are exposed
and unexposed, find out who got the disease.
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Prospective vs.
Retrospective Cohort
►Prospective: start with exposed and
unexposed groups, wait for the
outcome
►Retrospective: both exposure and
outcome have already happened, but
groups are still made based on
exposed or unexposed
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Strengths of cohort study
►Not only can you look at risk, you
can calculate how many people
actually get the disease (incidence
rates)
►Since you enroll subjects before
the outcome, you can measure
multiple exposures without recall
bias
►Best for rare exposures
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Some problems with cohorts
►Cohort studies may take a long time
►Cohort studies may require a large
number of people especially if the
outcome is uncommon
►Both of these make cohort studies
expensive
►Attrition of study group
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1.Selection of study subjects
►General population
►Select group…. Special exposure….
Degree or duration of exposure
2.Obtaining data on exposure
►Cohort members
►Review of records
►Medical examination/special tests
►Environmental surveys
Elements of Cohort
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3.Selection of comparisons group
►Internal comparisons… basis of degree /
levels of exposure
►External comparison
►Comparison with general population
►Periodic medical examination
►Reviewing physician n hospital records
►Surveillance of death record
►Mailed questionnaires, tele calls
4.Follow - up
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5.Analysis
►Incidence rates of outcome among
exposed n unexposed
►Estimate of risk
►Risk estimate done in terms of-
● Relative risk … strength of
association b/w risk factor n disease
● Attributable risk
 In diff in incidence rates of disease b/w
exposed grp n non exposed
 Extent the disease under study can be
attributed to exposure
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Relative risk v/s Attributable risk
►RR is imp in etiological enquires
►Inc RR … inc cause n effect
association
►AR .. Impact of successful
preventive or public health prog
might hv red the problem
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Example – What type of study
is this?
►In late 1840’s/early 1850’s London had
several outbreaks of cholera
►Snow hypothesized that the source of
water from a polluted area of the
Thames was the cause of the cholera
►He identified three water companies
that supplied the same neighborhoods
in London: 2 got their water from one
site on the Thames, the other from a
different area
►He then searched records for the
cholera deaths from these different
households/neighborhoods
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Results
# houses # deaths
Rate
Southwark & 40,046 1,263
3.15%
Vauxhall Cos
Lambeth Co 26,107 98
0.38%
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What is the relative risk?
►RR = Rate in exposed/rate in unexposed
►RR = (1263/40046)/(98/26107)
►RR = .0315/.0038
►RR = 8.3
►If you get your water from one of the
two bad companies, you are 8.3 times
more likely to die from cholera
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22/03/06
Experimental StudyExperimental Study

Experimental studies
►Final / definative step
►Direct intervention
Only Results from
Experimental Studies
Can Demonstrate
Cause and Effect
Relationships
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Subjects
random
allocation
Group 1
several
subjects
Group 2
several
subjects
Treatment 1
Treatment 2
Compare
22/03/06 www.indiandentalacademy.com

Clinical trials
►Diff types :
● Prophylactic trials
● Therapeutic trials
● Safety trials
● Effectiveness trial
● Risk factor trial- stop smoking nd
see
● Efficiency trial
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►Phases of trials :
● Phase 1
 Fraction dose – body fun.,drug metabolism –
‘Research Beds’
● Phase 2
 Assess effectiveness, determine dose, investigate
safety of drug or device
● Phase 3
 Only on consent
 Effectiveness,safety,long term effects
 Strict monitoring, follow up…
● Phase4
 Trial in normal field / prog setting
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Field trials
►In hospitals & clinics…
►Same rigour & qualifications as for
clinical trials
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22/03/06 www.indiandentalacademy.com

►Advantages of experimental
approach over observational
● Ability to manipulate or assign the
independent variable
● Ability to randomize subjects to exp
n control groups
● Ability control confounding n
eliminate sources of spurious assoc.
● Ability to ensure temporarity
● Ability to replicate findings
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►Limitations of experimental study
● Lack of reliability
● Difference in extrapolation
● Ethical problem
● Diff in manipulating the independent
variable
● Non – representativeness of samples
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Algorithm for
classification
of types of
clinical
research
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Contruction of research design
►Statement of problem:
● Precise & clear… clarifying &
focousing chosen topic.
►Relevance
● Why, its importance & priority
►Fields of application of research
● How results will help & whom…
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►Review of literature
● Existing knowledge
● Similar investigations – results
● Thorough & critical review – prevent repetitions
● Helps in Refining statement of problem
 Identifying study variables
 Formulation & selection of hypothesis
 Familiarity to various methods
● Sources of information:
– Books in libraries
– Indices
– Computer based literature e.g PUBMED.MEDLINE…
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►Statement of objectives
● Goal to be achieved…
● General objectives
– e.g Whether or not new vaccine should be
incorporated into public health prog.
● Specific objectives
– e.g evaluating new vaccine to determine
degree of protection attributable to
vaccine in study population by comparing
vaccinated & unvaccinated groups
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►Variables
● Independent variables – cause, risk
factor, determinant
● Dependent variable – effect, result,
disease
● Confounding variables
● Background variables
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►Statement of research hypothesis:
● Tentative prediction or explanation
of relationship b/w 2 or more varia.
● Not a haphazard guess …
● relationship b/w independent &
dependant variable
● Different types :
 Null hypothesis
 Alternate hypothesis
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► Research methodology
● Summary of methodology( 150 words)
● Research design
 Selection of research strategies
– Descriptive
– Analytical
– Experimental
 Selection of research setting
 Sampling
 Use of controls
 Study instruments
– questionnaires
– Medical examination
– Laboratory tests
 Plans of data collection
– Organization of study
– Training of data collection team
– Plans of pilot study
– Collaboration among institutions
 Plan for analysis & interpretation
– Design of analysis
– Plans for processing,coding ,sorting of data
– Choice of statistical analysis
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Ethical Considerations…
►3 principles :
● Beneficence
● Respect for rights
● Justice
►Declaration of Helsinki
● Scientific principles
● Qualified personnel
● Careful assessment of risk Vs benefit
● Rights of subject
● Accuracy of research results
● Subjects to be well informed
● Informed consent
● Subject free to abstain or withdraw any time
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?
or
……Conclusion
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Just get out
and do it!
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List of references:
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That’s all
Thank you
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Research methodology 2

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Research methodology 2