1- Research question 2- Study designs 3- Data collection methods and tools 4- Data presentation

1. Introduction
Research Methodology
Nouran Hamza, MSc
Freelance biostatistician

2. The Process of Research
Identify the
Research Problem
Review the
Literature
Report
and
Disseminate Research
Specify a
Research
Purpose
Collect Data
Interpret
the Research
Analyze Data

3. Identify research problem

4. Identify research problem

6. Cross-sectional studies
• An “observational” design that surveys
exposures and disease status at a single point
in time (a cross-section of the population)
time
Study only exists at this point in time

7. Cross-sectional Design
time
Study only exists at this point in time
Study
population
No Disease
Disease
factor present
factor absent
factor present
factor absent

8. Cross-sectional Studies
• Often used to study conditions that are relatively
frequent with long duration of expression (nonfatal,
chronic conditions)
• It measures prevalence, not incidence of disease
• Example: community surveys
• Not suitable for studying rare or highly fatal diseases
or a disease with short duration of expression

9. Cross-sectional studies
• Disadvantages
• Weakest observational design,
(it measures prevalence, not incidence of
disease). Prevalent cases are survivors
• The temporal sequence of exposure and effect
may be difficult or impossible to determine
• Usually don’t know when disease occurred
• Rare events a problem. Quickly emerging
diseases a problem

10. Epidemiologic Study Designs
• Case-Control Studies
–an “observational” design comparing
exposures in disease cases vs. healthy
controls from same population
–exposure data collected retrospectively
–most feasible design where disease
outcomes are rare

11. Case-Control Studies
Cases: Disease
Controls: No disease

12. Study
population
Cases
(disease)
Controls
(no disease)
factor present
factor absent
factor present
factor absent
present
past
time
Study begins here

13. Case-Control Study
• Strengths
– Less expensive and time consuming
– Efficient for studying rare diseases
• Limitations
– Inappropriate when disease outcome for a specific exposure
not known at start of study
– Exposure measurements taken after disease occurrence
– Disease status can influence selection of subjects

14. Hypothesis Testing: Case-Crossover Studies
• Study of “triggers” within an individual
• ”Case" and "control" component, but information
of both components will come from the same
individual
• ”Case component" = hazard period which is the
time period right before the disease or event
onset
• ”Control component" = control period which is a
specified time interval other than the hazard
period

15. Epidemiologic Study Designs
• Cohort Studies
– an “observational” design comparing
individuals with a known risk factor or
exposure with others without the risk factor or
exposure
– looking for a difference in the risk (incidence)
of a disease over time
– best observational design
– data usually collected prospectively (some
retrospective)

16. time
Study begins here
Study
population
free of
disease
Factor
present
Factor
absent
disease
no disease
disease
no disease
present
future

17. Timeframe of Studies
• Prospective Study - looks forward,
looks to the future, examines future
events, follows a condition, concern or
disease into the future
time
Study begins here

18. Prospective Cohort study
Measure exposure
and confounder
variables
Exposed
Non-exposed
Outcome
OutcomeBaseline
time
Study begins here

19. Timeframe of Studies
• Retrospective Study - “to look back”,
looks back in time to study events that
have already occurred
time
Study begins here

20. Retrospective Cohort study
Measure exposure
and confounder
variables
Exposed
Non-exposed
Outcome
OutcomeBaseline
time
Study begins here

21. Cohort Study
• Strengths
– Exposure status determined before disease detection
– Subjects selected before disease detection
– Can study several outcomes for each exposure
• Limitations
– Expensive and time-consuming
– Inefficient for rare diseases or diseases with long
latency
– Loss to follow-up

22. Identify research problem

23. Identify research problem

24. Literature review
• Definition:
• A literature review is an assessment of a body of
research that addresses a research question.
• Purpose:
• A literature review:
• Identifies what is already known about an area of study
• It may also:
• Identify questions a body of research does not
answer
• Make a case for why further study of research
questions is important to a field

25. Literature review

26. Literature review
Process:
• It is a research journey with several steps:
• Framing a research question
• Searching relevant bodies of literature
• Managing search results
• Synthesizing the research literature
• Writing an assessment of the literature
• The process is iterative—as you gain
understanding, you’ll return to earlier steps to
rethink, refine, and rework your literature review.

27. Specify a research purpose
To be effective, a statement of purpose should
be:
• Specific and precise - not general, broad or
obscure
• Concise - one or two sentences
• Clear - not vague, ambiguous or confusing
• Goal-oriented - stated in terms of desired
outcomes

28. Data collection

29. Data collection

30. Data collection

31. Data collection
types of variables

32. Data presentation and analysis
tabular presentation: simple

33. Data presentation and analysis
tabular presentation: complex

34. Data presentation and analysis
graphical

35. Bar chart

36. histogram

37. Pie chart

38. Line graph

39. Scattered