This was given as a part of the course of Research & Evidence-Based Medicine given to fourth-year medical students (2018)

1. Research Methodology and
Evidence Based Healthcare (EBHC481)
DIFFERENT TYPES OF
RESEARCH
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD1
Lecture 3
Level 8
Year 4

2. Research Methodology and
Evidence Based Healthcare (EBHC481)
OBJECTIVES
• Explain classification of research
• Discuss different types of research
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD2

3. Research Methodology and
Evidence Based Healthcare (EBHC481)
Classification of Research
There are varieties of ways through which we may classify it into
different categories.
(A) On the basis of nature of information:
On the basis of nature of information we can classify the research into
two types;
(i) Qualitative Research: When information is in the form of qualitative
data.
(ii) Quantitative Research: When information is in the form of
quantitative data.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD3

4. Research Methodology and
Evidence Based Healthcare (EBHC481)
Classification of Research
(B) On the basis of utility of content or nature of subject matter of
research:
On the basis of these criteria we can categorize the research into
two categories.
(i) Basic/ Fundamental /pure or Theoretical Research: Its utility is
universal.
(ii) Experimental or Applied Research: Its utility is limited.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD4

5. Research Methodology and
Evidence Based Healthcare (EBHC481)
Classification of Research
(C) On the basis of approach of research:
We may classify research into two different categories.
(i) Longitudinal Research: Examples of this category are historical,
Case study and Genetic research.
(ii) Cross-Sectional Research: Examples of this category are
experimental and Survey Research.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD5

6. Research Methodology and
Evidence Based Healthcare (EBHC481)
Classification of Research
(D) On the basis of method of research :
On the basis of research method we may classify a research into
five different categories.
(i) Philosophical Research: It is purely qualitative in nature and we
are focusing on the vision of others on the content of research.
(ii) Historical Research: It is both qualitative as well as quantitative
in nature and deals with past events.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD6

7. Research Methodology and
Evidence Based Healthcare (EBHC481)
Classification of Research
(D) On the basis of method of research cont. :
(iii) Survey Research: It deals with present events and is quantitative in
nature. It may further be sub-divided into; discretional, correlational and
exploratory type of research.
(iv) Experimental Research: This is purely quantitative in nature and deals
with future events.
(v) Case-Study Research: It deals with unusual events. It may be qualitative as
well as quantitative in nature depending upon the content.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD7

8. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
According to the type of data
Quantitative
• Uses the analysis of numerical data
• Involves large number of participants representative of the population of interest
• Aims at using statistics to explain the observations
• Uses various instruments to collect data (questionnaires, monitors, other tools)
Qualitative
• Data are in the form of words, pictures, and objects
• Involves small number of participants
• Aims at providing a complete and detailed description
• Researcher serves as data-gathering instrument
Both the qualitative and the quantitative research methods are governed by the scientific principles.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD8

9. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
According to availability of data at the beginning of research
Primary
• Data does not exist at the beginning of the study and a researcher has
to collect the data using appropriate methods
Secondary
• Secondary analysis of existing epidemiological data
• Synthesis of existing research
• Main method is a systematic review with or without meta-analysis
(a statistical technique used to pool data from independent studies)
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD9

10. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
According to research setting
Public health
• Considers factors affecting health of a population
Clinical research
• Pertains to the assessment of safety and effectiveness of medications and diagnostic
procedures and devices
• It is conducted on humans in four phases, ending with post-marketing surveillance
Pre-clinical research (microbiology, physiology, biochemistry, molecular biology, etc.)
• Research in basic science, precedes clinical trials
• Involves animal experiments, human tissue, or cell lines
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD10

11. Research Methodology and
Evidence Based Healthcare (EBHC481)
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD11
Phases of clinical Trial
Phase 0:
From the work bench to humans is the agent hitting its target?
Phase 1
Deciding on dose considering dose limiting toxicity and
maximum tolerance dose.
Phase 2
Drug activity , safety and feasibility evaluation
Phase 3
Clinical outcomes compared to a control arm
Phase 4
Post marketing surveillance- long term safety

12. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
According to study design
I- Observational
• Does not involve interventions on the part of the investigator
• Descriptive (examine patterns of diseases and risk factors)
II- Case reports and case series
• Describe the experience of a single patient or a group of patients with a similar diagnosis
• Routine data
• Prevalence surveys
• Clinical audit uses research methods but does not necessarily constitute the scientific method of research
• Advantages of descriptive studies: useful for hypothesis formulation
• Disadvantages of descriptive studies: lack of comparison group, case reports cannot be used to test the
presence of a statistical
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD12

13. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
III- Analytic (examines the associations between risk factors and diseases)
A. Cross-sectional
• Exposure and outcome assessed at the same time
• Prevalence of diseases and risk factors in a population
• Advantages: relatively quick, easy, and inexpensive, can study multiple exposures
and outcomes
• Disadvantages: temporal sequence and causal association between exposure and
outcome cannot be established
• examples: Health Survey for England (UK) and National Health and Nutrition
examination Survey (US) are both being conducted as a series of cross-sectional
examination
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD13

14. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
B - Case-control
• Subjects are selected on the basis of having a disease (cases , controls)
• Groups are compared with respect to the proportion of having a history of exposure
• advantages: relatively quick and inexpensive; suitable for the evaluation of the
diseases with long latent periods and for rare diseases; can assess multiple risk factors
for a single disease
• Disadvantages: cannot directly calculate the incidence of disease unless the study is
population-based; difficult to establish temporal sequence and causal association
between exposure and outcome; prone to recall bias; inefficient for rare exposures
• Example: INTERHEART study (a global case-control study of risk factors for acute
myocardial infarction)
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD14

15. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
C- Cohort
• Can be prospective (disease has not occurred at the beginning of the study) and retrospective (disease has occurred at
the time the study is initiated)
• Subjects are selected on the basis of having the exposure and are followed up over time to assess the outcome
• Direct measurement of disease incidence
• Advantages: can directly calculate the incidence of disease among exposed and non-exposed; can elucidate temporal
relationship between exposure and outcome; bias in exposure assessment is minimized (prospective studies)
• Disadvantages: expensive and time-consuming (especially if prospective); inefficient for rare diseases; requires
availability of adequate records (retrospective); losses to follow-up may substantially affect the validity of the results
• Examples: Nurses’ Health Study, Health professionals Follow-up
Study, atherosclerosis risk in Communities Study,
Prospective Investigation into Cancer and Nutrition.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD15

16. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
IV- Experimental
• Involves interventions
• Randomized clinical trials
• Efficacy (explanatory) trials—tests the efficacy of a treatment (or an
intervention) among highly selected participants and under controlled
conditions
• Effectiveness (pragmatic) trials—tests the efficacy of a treatment
(or an intervention) under real conditions among participants who were
not highly selected and provides useful information about the practice
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD16

17. Research Methodology and
Evidence Based Healthcare (EBHC481)
Different types of research
IV- Experimental cont.
• Are deemed to be the gold standard in clinical research
• Resembles a controlled experiment in the laboratory
• Subjects are enrolled on the basis of their exposure (treatment) status
• Random allocation of the treatment in a sufficiently large sample size
• Provides greater assurance about the validity of the findings than
observational studies
• Advantages: provides the most direct epidemiologic evidence on which to
judge whether an exposure prevents or causes a disease
• Disadvantages: ethical concerns; costs; feasibility; non-compliance
• examples: Clinical Trial of estrogen plus progestin in post-menopausal women.
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD17

18. Research Methodology and
Evidence Based Healthcare (EBHC481)
REFERANCE BOOK
WRITTEN AND COMPILED BY DR. EMAN ABD ALHALIM MD, PHD18
Oxford Handbook of
Clinical and Healthcare Research
Sumantra (Shumone) Ray, et al
2016
ISBN 978–0–19–960847–8
Oxford University Press 2016
Great Clarendon Street, Oxford,
OX2 6DP,
United Kingdom