Observational studies

1. Presented By :
NAME : SUSMITA GHOSH.
COURSE : B.PHARM.
YEAR :4th . SEM : 8th
ROLL : 19301920115
SUBJECT NAME :
BIOSTATIC AND RESEARCH
METHODOLOGY
SUBJECT CODE : PT817
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2. INTRODUCTION
Statistics is the use of science to collect and organize data into
patterns or trends. A statistical study gathers information
on a population or group of individuals and tries to
generalize the results for individual use. One statistical
study example is the observational study. These studies
commonly take place early in health research on a
particular topic as they are usually cost-effective at
obtaining large amounts of general data about a population
quickly. The distinguishing factor of an observational
study is that there is no treatment or intervention done
by researchers.
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Analytical Study Design
Observational Studies Experimental Studies

3. OBSERVATIONAL STUDY
Observational studies are called epidemiological study
designs. These are the only practicable methods of studying
various problems .
In observational study , subjects are not randomized to
the exposed or unexposed groups , rather the subjects
are observed in order to determine both their exposure
and their outcome status and the exposure status is thus
not determined by the researcher.
Observational studies are ones where researchers observe the
effect of a risk factor, diagnostic test, treatment or other
intervention without trying to change who is or isn’t
exposed to it.
This study , researchers only observe the subjects and do not
interfere to influence the outcome.
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4. TYPES OF OBSERVATIONAL STUDIES
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Observational
Study
Cohort Study
Prospective
Cohort Study
Retrospective
Cohort Study
Case-Control
Study
Cross-
Sectional
Study

5. COHORT STUDY
Cohort Studies are used to study – Incidences (the number of
times disease happens.) , Causes , Prognosis (predicting or
expected development of a disease , including whether the
sign and symptoms will improve or worsen or remain stable
over time.)
They can be used to distinguish between cause and effect.
This is a type of observational study in which no intervention
(a treatment , procedure or other action taken to prevent or
treat disease or improve health in other ways) for the sake of
the study.
‘Cohort’ is a group of individuals having some common
features. In the context of drug research , the common
feature is that all study subjects have taken a particular drug.
Occurrence of events in users and nonusers of the drug is
compared.
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6. PROSPECTIVE COHORT STUDY
A prospective study watches for outcomes , such as the
development of a disease , during the study period and relates
this to other factors such as suspected risk or protection factors.
The study usually involves taking a cohort of subjects and
watching them over a long period.
The investigator then measures a variety of variables that might be
relevant to the condition.
In the prospective design , all patients who receive the study drug
are followed up for therapeutic outcomes or adverse effects. A
matching group of patients who have not receive the drug is
identified and followed up to severe as ‘blank’.
After a time the people in the sample are observed to see whether
they develop the outcome of interest – if the do not develop the
outcomes of interest are used as ‘controls’ and another cohort
group treated with the agent of interest used as ‘treated’.
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7. RETROSPECTIVE COHORT STUDY
Retrospective meaning – Looking backward on the past , on what
has already taken place.
A retrospective study looks backwards and examines exposures to
suspected risk or protection factors in relation to an outcome that
is established at the start of the study.
In the retrospective cohort study , health records of a population are
scrutinized for exposure to the study drug and the subsequent
beneficial / adverse events.
These studies used data , already collected for other purposes.
The study period may be many years but the time to complete the
study is as long as it takes to collect and analyze the data.
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Study Design Of COHORT STUDY

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CASE – CONTROL STUDY
In case control study two existing groups differing in outcome
are identified and compared on the basis of some supposed
casual attribute.
Here researchers identify people with an existing health
problem (“cases”) and a similar group without the problem
(“controls”) and then compare them with respect to
exposures.
It is a retrospective observational study.
For example : To study the effects of caffeine on sleep habits ,
treatment group would be people who regularly drink
caffeine and control group would match in age and gender
but wouldn’t regularly consume caffeine.
Studying the sleep habits of both groups could help
understand how caffeine affects sleep habits.

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Study Design of CASE-CONTROL STUDY

11. CROSS SECTIONAL STUDY
Cross-sectional study is a type of observational study that
analyzes data from a population at a specific point in time.
These studies are used to determine prevalence (proportion of
a particular population found to be affected by a medical
condition , typical; a disease or a risk factor such as
smoking at a specific time).
They are relatively quick and easy do not permit distinction
between cause and effect.
In the cross-sectional study , we split the sample population
into two groups , exposed and unexposed , and then
observed whether the participants in two groups have the
outcome.
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Study Design of CROSS-SECTIONAL
STUDY

13. ACKNOWLEDGEMENT
I would like to express my gratitude to Mr. Sougata
Mallick & Mr. Tanmoy Jash , for their guidance
and support.
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14. REFERENCES
1. Prof. Kokare Chandrakant , BIOSTATIC AND
RESEARCH METHODOLOGY , Nirali Prakashan ,
2nd edition , 2022 , p(13.4)
2. Dr. Dwivedi.S , Dr. Rageeb , Dr. Satyaendra ,
BIOSTATIC AND RESEARCH METHODOLOGY ,
Pee Vee Publishers , 2022 , p-88.
3. Brown Austin , 03/30/2022 , OBSERVATIONAL
STUDY IN STATISTICS , 14.01.2023.
https://study.com/academy/lesson/observational-study-
in-statistics-definition-example.html.
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