Types of research, sampling techniques, statistical test

1. Research Capacity
Building Workshop
Presentation
Dr. Deepa Devhare
Assistant professor
Dept of Microbiology

2. Content:
• Research
• Types of research methodologies
• Research cycle
 Research question
 Study design
 Components of research
 Statistical analysis of results
• Ethics in research

3. Research
• process of steps used to collect and analyze information to
increase our understanding of a topic or issue".

5. Research cycle

6. 1. Research question
A question that a study or
research project aims to
answer.

7. 1. Research question

8. Structure of the Research Question
PICOT
P: Patients, Population, Participants, Problem
I: Intervention, Independent Variable, Input variable,
Index Test
C: Camparator, Comparision,Control
O: Outcome(Health outcome), patient oriented
outcome
T: Timed Outcome

10. Eg. Researcher wants to study effect of folic acid
supplementation on gingival overgrowth in pediatric patients
taking phenytoin as a treatment
Formulating a research question in PICOT structure
P: Children aged 6-15 yrs recently started on phenytoin
monotherapy
I: Folic acid supplementation0.5mg/day
C: Placebo
O: Incidence of any degree of gingival overgrowth
T: 6months

11. 2. Research/Study Design
 refers to the overall strategy that you choose to integrate the
different components of the study in a coherent and logical
way, thereby, ensuring you will effectively address the
research problem
 it constitutes the blueprint for the collection, measurement
and analysis of data.

12. Study design
Descriptive
 describes the
phenomenon as
it exists.
 Used to identify
and obtain information
on the characteristics
of a particular issue
Analytic
 Aims to
understand
the phenomenon

13. Study design

14. Types of
study
designs
Cross sectional study
Case control study
Cohort study
Diagnostic study
Randomised control trials

15. 1. Cross
sectional
study

17. 2. Case control studies
 Analytical observational study
 Always retrospective

20. 3. Cohort study
 Cohort -derived from latin word meaning an
enclosure, company or crowd
 In research, the cohort is a group of people with
something in common usually an exposure or
involvement in a defined population group

21. COHORT
STUDY

24. Cohort study

26. 4. RANDOMISED CONTROL TRIALS

29. Hierarchy Based on Study Designs

31. Components of research
Variables Sample Bias Outcome Data

32. Variable: refers to a person, place, thing, or phenomenon
that you are trying to measure in some way
Independent
variable
• Input variable
• can be changed
and tested
Dependent
variable
• Output variable
• Directly affected
by input
variable
not studying for a test Test score

33. Study population
• refers to a smaller,
manageable version of a
larger group.
• It is a subset containing the
characteristics of a larger
population.
Accessible
population

35. Probability sampling

36. Non probability sampling

37. Independent variable
• can be changed and tested.
Random error-
Difference between
study finding and truth
due to chance
Systematic error
Difference between study
finding and truth due to
methodological issues
Researcher misreading the weight of
study participanats
uncalibrated weighing
machine giving wrong
readings
What can go wrong in
research?

38. TYPES OF BIAS
Selection bias
Allocation bias
Performance bias
Detection bias
Attrition bias
Interpersonal bias

39. Outcome
Types of outcome Example
Hard outcome Diabetes mellitus
Soft outcome Impact of DM on
quality of life
Surrogate outcome HBA1C
Patient centric
outcome
Diseases/not diseases
Cured /not cured
• final product or end result; consequence; issue.
• conclusion reached through a process of logical thinking.

40. Data and data handling
• Anything that can be grouped based on
comparable parameters IS DATA.
• Data Handling is the process of gathering,
recording, and presenting information that is
helpful to analyze, make predictions and choices.

42. Introduction to Statistical tests
Before analysing data we need to know whether
data is normally distributed or not?
Normal distribution
Skewed distribution

43. Normal distribution (Gaussian curve)
• its mean , median and mode are all
equal to one another
• The distribution then falls
symmetrically around the mean,
the width of which is defined by
the standard deviation.

44. Skewed distribution
• Appearance of graph:Asymmetrical curve
• Skewness: If SD is >1/2 of mean
• Median far away from mean

46. Statistical
analysis for
diagnostic study
designs
Sensitivity
Specificity
Positive predictive
value
Negative
predictive value

48. • human research to be approved by an Institution
Ethics Committee
• Informed consent necessary from study
participants
• Responsibility of principal investigator
Ethical committee approval and
informed consent