1. RESEARCH DESIGN
G.VAISHNAVI

2. RESEARCH DESIGN
• Research design is the planned structure and strategy of investigations of answering the research question. It is
the constitute or blueprint the researcher select to carry out his/her study.
• Research design is divided into two types:
• Non-interventional studies.
• Interventional studies.
Research Design
Non-interventional Interventional
Analytical or
comparative
Exploratory
Descriptive
Experimental Quasi-
Experimental

3. Non-interventional studies:
• The researcher just describes and analysis researchable objects or situations but does not intervene.
Interventional studies:
• The researcher manipulates objects or situations and measures the outcome of the manipulation. The strength of
the experimental study is by randomisation the researcher eliminates the effect of extraneous variables.
• Experimental design is the only type of study design that can actually prove caution.
NON-INTERVENTION STUDIES:
• Exploratory Design or study:
• It is a small scale study of relatively short duration which is carried out when little is known about the situation or
a problem.
• Eg; A national AIDS control program wishes to establish counselling services for HIV positive and AIDS patients
but lacks information on specific needs patients have for support.
• To explore these needs a no of in depth interviews are held with various categories of pts(male, female, single,
married) with some counsellors working in a program that is already underway.
• When doing exploratory studies we describe the needs of various categories of patients and the possibilities for
action. We may want to go further and try to explain the differences we observe( the need of male and female
AIDS patients) or to identify cause of problems. Then we will need to compare groups.

4. Descriptive study or Design:
• It is the systematic collection and presentation of data to give a clear picture of a particular situation.
Descriptive studies can be carried out on a small or large scale. It describes a characteristics of one or a limited
number of cases. A case may be a patient or a village, etc. such a study can provide useful insight in to a problem.
• Eg;-analysis of proprioception between normal, young and old age people.
• Evaluation coverage survey, biological, physical and behavioural study of people, prevalence survey, socio-
economic characters of people, knowledge, attitude, opinions, personality.
• Descriptive case studies leads to construction of theories may be time consuming. If they are of short duration, we
may call the study as exploratory studies.
Analytical or comparative study/design:
• An analytical study attempts to establish causes or risk factors of certain problem. This is done by comparing two
or more groups. Some of which have or develop the problem and some of which may not develop the problem.
• Three commonly used analytical studies are
1. Cross sectional comparative study
2. Case –control study ( Retrospective study)
3. Cohort study (Prospective study)

5. Cross sectional comparative study:
When a cross sectional survey focus on comparing as well as describing groups. Eg, a survey on
malnutrition may wish to establish the percentage of malnourished children in a certain population, socio economic,
physical variables etc that influence the availability , feeding practices and the knowledge, beliefs and opinions that
influence these practices. The researcher will not only describe these variables but by comparing malnourished and
well nourished children and try to determine which socio economic, behaviour and other independent variables have
contributed to malnutrition.
Case controlled study/Design:
It is the retrospective study(i.e) present to past. Here the researcher/investigator compares one group among
whom problem is present with another group called control/comparison group where the problem is absent to find
out what factors have contributed to the problem.
Diagram of case control study
Risk factor absent
Risk factor present
Risk factor absent
Risk factor present
Cases
Control
Compare

6. • Eg:- In a study of the causes of neonatal death by investigator/researcher first select the cases( children who died
within the first month of life) and controls (children who survived their first month of life).
• The researcher then interview their mothers to compare the history of these two group of children to determine
whether certain risk factors are more prevalent among the children who died than among the children those who
survived.
3) COHORT STUDY
• It is a prospective study (i.e) present to future. In a cohort study a group of individuals exposed to risk factors (
study group) is compared with the group of individuals not exposed to the risk factors ( control group)
• The researcher follows both the group over time and compares the occurrence of the problem that the researcher
expects to be related to the risk factor in the two groups to determine whether the greater proportion of those with
the risk factors are indeed affected.
DIAGRAM OF COHORT STUDY
Problem absent
Problem present
Problem absent
Problem present
Compare
Exposed to risk
factors
Control group Not exposed to
risk factor
Study group

7. Eg;- suppose to compare the group exposed to risk factors (smoking) and the group not exposed to the risk factors(ie)
smoker and non smokers a nd follow both the groups over a period of time whether the study group develops a higher
prevalence of lung cancer than the control group.
INTERVENTION STUDIES :
Two types :
 Experimental design
 Quasi-Experimental design
EXPERIMENTAL DESIGN :
In the experimental study individuals or subjects are randomly allocated to atleast two groups. one group is subject to
and intervention or experiment while the other group is not subject to intervention.
The outcome of the intervention is obtained by comparing the two groups.
Experiment:
It is a scientific investigation in which observations made and data are collected according to a set of well defined
criteria.
Experimentation is the most scientifically sophisticated research method.
Characteristics of experimental designs:
A true experiment is characterized by the following properties :
1. Manipulation.
2. Control.
3. Randomisation

8. MANIPULATION:
• It is a process in which the researcher manages the independent variable (IV) in order to study the affect on
the dependent variable(DV).
• I.V is cause and D.V is effect (ie) the change in the D.V is presumed to be caused or associated with I.V.
Therefore. manipulation refers to the fact that the researcher does something with the I.V.
CONTROL :
• It is the basic element of experimentation. Th experiment must be organised so that the extraneous factors are
prevented from operating and confusing the outcome which is to be appraised.
• Control is acquired by manipulating , randomization by careful preparation of the experiment protocols and
by the use of comparison group (or) groups.
• The researcher used both both experimental and control groups whose units as a first randomly selected from
the target population and then randomly assigned to either experimental of control group.

9. RANDOMIZATION :
The term random essentially means that every subject has one equal chance of being assigned to any group.
Randomization in the process that ensures every unit in the target population has an equal chance of being
chosen for the study sample and then ensure that each unit in the study sample has equal chance of being
assigned to either experimental or control group.
EXAMPLE 1 :
Selection of 40 workers from cotton mill by random sampling and again allotted to both group of 20 each by
random sampling. Data collected for experimental group chest physio was given and for control group no
intervention was given. Again data is collected and then compared.
EXAMPLE 2 :
A researcher plans to study the effect of new drug to plan to include 40 patients in the study on a random basis.
One group will receive the experimental drug while the other group will continue to receive the standard
treatment then compare the outcome of the both experimental & control group find any significant difference.

10. Diagram of Experimental Design :
Target Population
(Study population)
Control Group
Sample population
(Randomization)
Study Group
Compare
First Data Collection
No Intervention (or) Manipulation
Second Data Collection
Second Data Collection
(after intervention)
Intervention (or) Manipulation
First Data Collection

11. QUASI-EXPERIMENTAL DESIGN : In a quasi experimental study at least one characteristics of true experiment is missing
either randomization or use of all separate control groups or sometimes both. Quasi experimental study however includes
manipulation of an independent variable that serves as an intervention.
• One of the most common quasi experiment design uses 2 or more groups. One of which serves as a control group in which no
intervention takes place.
• Both groups are observed before as well as after the intervention, to test if the intervention has made any difference. The subject
in the two groups(study of control) have not been randomly assigned.
Diagram of Quasi Experimental Design with 2 groups :
Example:
A researcher plans to study the effect of health education on the level of participation of a village population in an immunization
campaign, the researcher decides to select one village with health education session on immunization will be given and another
village that will not receive health education to serve as a control. The immunization camp will be carried out in the same manner in
both village. A survey will be undertaken to determine of immunization coverage in the village where health education was
introduced before the campaign significantly different from coverage in the village where the health education was not introduced.
Study group Intervention Study Group
After Intervention
Compare Group
After No Intervention
Control group

12. RANDOMIZATION :
• The term random essentially means that every subject has one equal chance of being assigned to any group.
• Randomization in the process that ensures every unit in the target population has an equal chance of being
chosen for the study sample and then ensure that each unit in the study sample has equal chance of being
assigned to either experimental or control group.
QUASI EXPERIMENTAL DESIGN WITH ONLY STUDY GROUP:
• Another type of design that is often chosen because it is quite easy to setup only one group in which an
intervention is carried out.
• Situation is analyzed before and after intervention to test there is any differences in the observed problem
• This is called before –after study
• EXAMPLE; Pain before and after treatment.
Study group
(Before) Intervention Study Group
(After)
Compare

13. Advantages: Confidence
Hypothesis builds researcher's confidence in his results
sound hypothesis gives direction to the enquiry.
God hypothesis enriches theory (theory is an elaborate hypothesis)
Characteristics of hypothesis:-
• Hypothesis should be stated clear and precise otherwise the inferences drawn on its basis cannot be taken
as reliable
• Hypothesis should be testable.
• Hypothesis should state relationship between variables if it happens to be a relational hypothesis.
• It should be stated as far as possible in most simple terms so that the same is easily understandable by all
concerned.
• It should be consistent with most known facts
• Hypothesis should be limited in scope and must be specific.

14. DIRECTIONALAND NON- DIRECTIONAL HYPOTHESIS:-
DIRECTIONAL HYPOTHESIS:
It specifies the expected direction of the relationship between independent and dependent Variable
Eg:-
1.Structured pre-operative education is more effective than structured post-operative education in reducing the
patients perception of pain.
2. There will be a decrease in post-text state anxiety scores in subjects treated with non-contact therapeutic
touch than in subjects treated with contact therapeutic touch.
NON-DIRECTIONAL HYPOTHESIS:
Indicates the existence of relationship between the variables but does not specify the anticipated direction the
relationship.
Eg. There will be a significant difference between post-test state anxiety to scores in subjects treated with non-
contact therapeutic touch and contact therapeutic touch.
RESEARCH HYPOTHESIS:
It is a statement about the expected relationship between variables.
Research hypothesis indicates what the outcome of the study is expected to be. It may be directional or non
directional

15. Purpose of research design.
To provide answers to research question
to control variances
Elements of research design:
• description of subjects (Who are the subjects).
• observation of variables (what are the variables).
• Measures of time (where observed).
• Selection of settings (where).
• Role of investigator / researcher (what)
Factors influencing the research designs:-
• Level of knowledge
• Nature of phenomena
• Natures of the purpose
• Ethical considerations.
• Feasibility
• availability of subjects.

16. • availability of facility & equipment
• Validity of data
• precision (very accurate)
• researcher's experience
• Cost
• Control
CRITERIA FOR GOOD RESEARCH DESIGN.
should be flexible, feasible economical
POPULATION AND SETTINGS:-
POPULATION ; Population is the entire aggregate of cases or elements that meet a designated set of
criteria.Eg: Physiotherapy in India
TYPES OF POPULATION
1) Target population It is the aggregate of cases about which the researcher would like to make
generalization Eg; No of physiotherapists in Tamilnadu
2) Accessible population It is the aggregate of cases that confirm to the designated criteria and that are
accessible to the researcher as a pool of subjects you a study. Also called sample population eg; No. of
Physiotherapy in JKKCOP

17. SAMPLING
Sampling refers to the process of selecting a portion of the population to represent the entire population.
Sample;
It is a small group of the population with its characteristics or It is a finite subset of population
CHARACTERISTICS OF GOOD SAMPLE
1) A good sample reproduces the characteristics of the population with the greatest possible accuracy
2) It should be free u from errors due to bias or due to deliberate selection of units (use of non probability sampling
technique)
3) It should be free from random sampling error
4) It should be adequate in size.
5). Sample should contain or consist of independent unite
STEPS INVOLVED IN SAMPLING PROCESS: 5 steps in the sampling process.
(i) Identify the target population.
(ii) identify the accessible sampled population.
(iii) specify the eligibility criteria.
(iv) Specify the sampling plan.
(v). Recruite the sample.

18. INCLUSION CRITERIA.
The criteria that specifies the characteristics that people in the population process is referred as inclusion /
eligibility criteria
EXCLUSION CRITERIA
The criteria that specifies the characteristics that people in the population must not possess is referred as
exclusive criteria
ELEMENT:
The element is the most basic unit from which information is collected
SAMPLE UNIT:
-Each member of population is sample unit.
STRATA;-
It refers to a mutually exclusive segment of a population established by one of more characteristics.