This document discusses different types of research designs. There are two main categories: observational and interventional designs. Observational designs include descriptive designs like cross-sectional studies and case reports, as well as analytical designs like case-control and cohort studies which examine relationships between variables. Interventional designs include randomized controlled trials which randomly assign participants to groups, and non-randomized trials. Randomized trials aim to eliminate bias but have limitations, while observational studies are useful for rare diseases and retrospective analysis but can be prone to biases. Proper research design helps minimize costs while obtaining relevant and reliable data to address the research problem.

1. Types of Research Design
Prepared By:
Abdulhakam Usman
1801020004
PharmD (PB) I year
Faculty of Pharmacy
Integral University Lucknow

2. Introduction
A research design can be defined as a framework of
methods and techniques chosen by researcher to
combine various components in a logical manner so
that research problem can be handled well.
According to Russell Ackoff, research design is the
process of making decisions before a situation has to be
carried out.

3. Characteristics of Research Design
1) Neutrality
2) Reliability
3) Validity
4) Generalization

4. Purpose of Research Design
1. To minimize the expenditure
2. To collect the relevant data and techniques
3. To provides blue prints for plan
4. To provide an overview for other experts
5. To provides a direction

5. Principles of Research Design
1. Formulating a problem
2. Review of literature
3. Formulating hypothesis
4. Selection of method(s)
5. Collect data
6. Analyse data
7. Interpret and report

6. 1. Define research problem
•Basically, there are 2 types of research problems,
first which relate to states of nature and second
which relate to the relationships between variables.
•The researcher must first decide the general area of
interest that he’d like to inquire into.

7. 2. Literature Review
•There is a conceptual literature which consists
theories and concepts and an empirical one
consisting of studies.
•Once the problem is formulate, the researcher
should take extensive literature survey connected
with the problem.

8. 3. Formulate Hypothesis
•It is a predictive and a tentative statement which
shows the relationship between Dependent and
Independent Variables and which can be tested.

9. 4. Preparing the Research Design
•The preparation of design facilitates research to
be efficient as possible.
•It may draw the conceptual structure of the
problem. There are several research designs, such
as experimental and non-experimental hypothesis
testing.

10. 5. Collect Data
• The method of collecting data should be selected
considering nature of investigation, objective and
scope of the inquiry, financial resources, available
time and degree of accuracy.
• Its 2 types are : -
• Primary data collection
• Secondary data collection

11. 6. Analyse Data
•Processing is done which includes editing, coding,
classification, tabulation, presentation and
measurement of data.

12. 7. Interpret and Report
• A report should be prepared by the researcher for
which he has done his work and both positive and
negative result should be reported.

13. Types of Research Design
1. Observational
a) Descriptive
i. Cross-sectional study
ii. Case reports
iii. Case series
b) Analytical
i. Case control
ii. Cohort studies
2. Interventional
a) Randomized
b) Non-randomized

15. 1. Observational Research Design
• Observational studies are those where the researcher is
documenting a naturally occurring relationship between the
exposure and the outcome that he/she is studying.
• For example, looking at the incidence of lung cancer in
smokers versus nonsmokers.
• Observational studies can be either descriptive or
analytical

16. A. Descriptive Research Design
• It is theory-based method of design which is created by gathering,
analyzing, and presenting of data.
• In descriptive design, a researcher is solely interested in describing
the case under study.
Examples: Do customers of company X prefer product A or product
B?
How prevalence is disease A in population B?

17. I. Cross-sectional Studies
•In medical research, and biology, a cross-sectional
study is prevalent.
•This study approach examines data from a
population or a representative sample of the
population at a specific point in time.

18. II. Case reports/Case-series
•A case report is a detailed report of the diagnosis,
treatment, response to treatment, and follow-up
after treatment of an individual patient. A case
series is group of case reports involving patients who
were given similar treatment.

19. Case reports/Case-series cont’d
• case series (also known as a clinical series) is
a type of medical research study that tracks subjects
with a known exposure, such as patients who have
received a similar treatment, or examines their
medical records for exposure and outcome.
• Case series may be consecutive or non-
consecutive.

20. B. Analytical Research Design
• Analytical studies attempt to test a hypothesis and
establish causal relationships between variables. In these
studies, the researcher assesses the effect of an exposure
(or intervention) on an outcome.

21. I. Case Control Study
• Is an analytical observation study, which has a
comparison (control) group.
• Case control studies are retrospective, and the main
objective is to determine whether or not an association
exists between a disease and a particular risk factor.

22. Case-control Study
Advantages
1. Is the most efficient design
in terms of time, money,
and effort.
2. Are also efficient in the
investigation of diseases
that have long latency
period.
3. Are useful to study rare
diseases.
4. Can study multiple risk
factors/exposures.
Disadvantages
1. If the frequency of exposure
is low, case-control studies
quickly become inefficient.
2. Many methodological
issues affect the validity of
the results of case-control
studies.
3. Are prone to selection and
recall bias.
4. It can be difficult to choose
an appropriate control

23. II. Cohort Studies
• Cohort is an analytical study which undertaken to obtain additional
evidence for or support the existence of association between
suspected cause and disease.
FEATURES OF COHORT STUDIES
• Cohort are identified prior to appearance of disease under
investigation.
• Study groups are observed over a period of time.
• The study usually proceeds from cause to effect

24. Frame Work of Cohort Studies

25. Types of Cohort Studies
1. Prospective Cohort Study
2. Retrospective Cohort Study

26. Difference between Case-Control and Cohort Study
Case-control study
1. Proceed from effect to cause
2. It produces results very quickly
3. It includes less subjects
4. It’s first approach for testing
hypothesis
5. CCS is less expensive and less
time consuming
6. Is used to study rare diseases
Cohort study
1. It proceeds from cause to effect
2. Results gets delayed
3. Required large number of subjects
4. Used for testing formed hypothesis
5. More expensive and more time
consuming
6. Not used in studying rare diseases

27. 2. Interventional Research Design
• An interventional trial is specifically designed to evaluate
the direct impacts of treatment or preventative measures
on disease.
• They are used to determine the effectiveness of an
intervention or the effectiveness of a health service
delivery. They can also be used to establish the safety, cost-
effectiveness and accceptability of an intervention.

28. • There are two types of intervention studies:
a) Randomised controlled trials and
b) Non-randomised or quasi-experimental trials.

29. Randomized controlled trials
• In an RCT, a group of participants fulfilling certain inclusion
and exclusion criteria is “randomly” assigned to two
separate groups, each receiving a different intervention.
• Random assignment implies that each participant has an
equal chance of being allocated to the two groups.

30. Advantages of Randomised Controlled Trials
1. Its study design eliminates confounding bias.
2. If properly designed and conducted, an RCT is likely to be
able to determine small to moderate effects.

31. Disadvantages of Randomised Controlled Trials
1. They are not always ethical.
2. Sample size can be too small.
3. Significant tests can be misleading.
4. They can be expensive.
5. RCTs may not have external validity.

32. Nonrandomized controlled clinical trials
• In this design, participants are assigned to different
intervention arms without following a “random”
procedure.
OR
• An experimental study in which people are allocated to
different interventions using methods that are not random.

33. Conclusion
• Descriptive and analytical research both play important
roles. The first shows what the data looks like while the
second examines cause and effect.
• Analytical research helps in many fields of study. For
example, these include psychology, marketing, medicine,
and other areas. Often, it’s used because it provides more
definitive information in answering research questions.

34. References
• Aggarwal R, Ranganathan P. Study designs: Part 2 – Descriptive
studies. Perspect Clin Res. 2019;10:34–6. [PMC free
article] [PubMed] [Google Scholar]
• Ranganathan P, Aggarwal R. Study designs: Part 1 – An overview and
classification. Perspect Clin Res. 2018;9:184–6.
• Schultz, K.F.& Grimes, D.A. (2002) "Sample Size slippages in
randomised trials: exclusions and the lost and wayward." The Lancet,
359, 781-85.