research methodology: an overview ahmed mandil, prof of epidemiology king saud university, riyadh,...

Research Methodology:An Overview

Ahmed Mandil, Prof of Epidemiology

King Saud University, Riyadh, KSA

Headlines

Health research Choice of subjects Data collection methods Sources of data Study designs (qualitative, quantitative) Choice of study design Health research proposal Literature review

Oct 24, 2009 2Research Methodology

Health Research

Lab research: applies knowledge of basic sciences towards development of procedures and strategies to prevent, control and understand mechanisms of health-related phenomena

Population-based (field) research: study of distribution, determinants, control measures of health-related phenomena in chosen populations, followed by application of suitable biostatistical techniques which may allow generalization of results

Healthcare-facility (clinical) research: application of epidemiological principles in research based in healthcare facilities, e.g. randomized clinical trials


Oct 24, 2009 Research Methodology

Research Characteristics

Has a clearly stated question(s) and hypotheses (null, alternative)

Has a specific plan of action Builds on existent knowledge Generates NEW data, which answers the

original question(s) Opens horizons for further enquiries and

research

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Subjects & Data Collection

Selected Units: individuals, groups Study Populations: cross-sectional,

longitudinal Data collection timing:

prospectively, retrospectively, combination

Data collection types: primary, secondary



Study Populations

Cross-sectional: where ONLY ONE set of observations is collected for every unit in the study at a certain point in time, disregarding the length of time of study as a whole (health surveys’ populations are of this type)

Longitudinal: where TWO-OR-MORE sets of observations are collected for every unit in the study, i.e. follow up is involved in order to allow monitoring of a certain population (cohort) over a specified period of time.

Dynamic: gains and loses members

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Data Collection Types

Primary: where the investigator is the first to collect the data. Sources include: medical examinations, interviews, observations, etc. Merits: less measurement error, suits objectives of the study better. Disadvantage: costly, may not be feasible.

Secondary: where the data is collected by OTHERS, for other purposes that those of the current study. Sources include: individual records (medical / employment); group records (census data, vital statistics)


Data Collection Sources

Routine systems (e.g. vital statistics: births / deaths; health insurance; communicable diseases)

Surveys (interviews; telephone; mail; self-administered)

Disease registries (hospital / community – based)

Sentinel event recording systems (health; disease; health services)


Study Design: Definition

A study design is a specific plan or protocol for conducting the study, which allows the investigator to translate the conceptual hypothesis into an operational one.


Study Designs: Types

Qualitative Quantitative

Experimental Observational

Basic Hybrid Incomplete


Types of quantitative designs

Observational designs: studies that do not involve any intervention or experiment.

Experimental designs: studies that entail manipulation of the study factor (exposure) and randomization of subjects to treatment (exposure) groups


Observational Designs

Exploratory: used when the state of knowledge about the phenomenon is poor: small scale; of limited duration.

Descriptive: used to formulate a certain hypothesis: small / large scale. Examples: case-studies; cross-sectional studies

Analytical: used to test hypotheses: small / large scale. Examples: case-control, cross-sectional, cohort.Oct 24, 2009 12Research Methodology

Cross-sectional Studies(Community health studies, surveys)

Characteristics: detects point prevalence; relatively common conditions; allows for stratification; different from surveillance / registers

Merits: feasible; quick; economic; allows study of several diseases / exposures; useful for estimation of the population burden, health planning and priority setting of health problems

Limitations: temporal ambiguity (cannot determine whether the exposure preceded outcome); possible measurement error; not suitable for rare conditions; liable to survivor bias

Effect measure: Odds Ratio + CI


Case - Control Studies

Characteristics: two source populations; assumption that non-cases are representative of the source population of cases.

Merits: least expensive; least time-consuming; suitable for study of rare diseases (especially NCDs)

Limitations: not suitable for rare exposures; liable to selection bias and recall bias; not suitable for calculation of frequency measures.

Effect measure: Odds Ratio + CI


Cohort Studies

Characteristics: follow-up period (prospective; retrospective)

Merits: no temporal ambiguity; several outcomes could be studied at the same time; suitable for incidence estimation

Limitations (of prospective type): expensive; time-consuming; inefficient for rare diseases; may not be feasible

Effect measure: Relative Risk + CI


Coh

ort

Desi

gn

timeStudy begins here

Studypopulation

free ofdisease

Factorpresent

Factorabsent

disease

no disease

disease

no disease

presentfuture


Experimental Designs

Types: Lab experiments; Randomized Clinical trials; Community interventions studies. These types are differentiated by: number of participants and duration

Merits: control of confounders Limitations: limited generalizability;

possibility of unethical randomization;

impracticability under some settings


Experi

menta

l D

esi

gn

timeStudy begins here (baseline point)

Studypopulation

Intervention

Control

outcome

no outcome

outcome

no outcome

baselinefuture

RANDOMIZATION


Choice of Study Design (I)

Depends on: Research Questions Research Goals Researcher Beliefs and Values Researcher Skills Time and Funds


Choice of Study Design (II)

Status of existent knowledge Occurrence of disease Duration of latent period Nature and availability of

information Available resources Time constraints



Health Research Proposal Components

Executive Summary Literature review & rationale Objectives & hypothesis Methodology Ethical considerations Chronogram Budget References Investigating team

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What is a good proposal ? Credible innovative research question Meticulously designed research plan Carefully selected research team Attractively presenting all of the above, so that it:

Communicates clearly & concisely Follows a logical outline Indicates merits and limitations of the plan, but Makes sure that merits do stand out (for a busy

reviewer)

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Literature Review Peer consultation Databases (search engines: e.g. Pubmed;

Medline; Ovid; IMEMR at WHO / EMRO website) Published literature (scientific journals) Published literature (electronic journals)

Grey literature (theses: masters / doctoral; reports: ministry of health / social affairs / annual statistics; national census, others)

Oct 24, 2009 Research Methodology 23

References

1. Porta M. A dictionary of epidemiology. 5th edition. Oxford, New York: Oxford University Press, 2008.

2. Fathallah MF, Fathallah MMF. A practical guide for health researchers. Cairo: WHO, 2004.

3. Rothman KF, Greenland S, Lash TL. Modern Epidemiology. 3rd edition. Philadelphia: Walter Kluwer, Williams & Wilkins 2008: 100-110.

4. Gordis L. Epidemiology. 4th edition. Philadelphia, Pennsylvania: Elsevier Science, 2008

5. Beaglehole R, Bonita R, Kjellstrom T. Basic epidemiolgy. 2nd edition. Geneva: World Health Organization, 2006


Thank you for your kind attention
