: A Research design is a logical and systemic plan prepared for directing research. It specifies the objectives of the study, the methodology and techniques to be adopted for achieving the objectives. It constitutes the blue print for the collection, measurement and analysis of data. It is the plan, structure and strategy of investigation conceived so as to obtain answers to research questions. A research design is the program that guides the investigator in the process of collecting, analyzing and interpreting observations.

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Index
▪ Research Design (Page 2 to 5)
▪ Introduction
▪ Need of Research Design
▪ Characteristics of a good Research Design
▪ Component of Research Design
▪ Different type of Research Design
▪ Sampling ( Page 6 to 9)
▪ Purpose of sampling
▪ Advantage of sampling
▪ Characteristics of a good sample
▪ Types of sampling

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Research Design
Introduction: A Research design is a logical and systemic plan prepared for directing research. It
specifies the objectives of the study, the methodology and techniques to be adopted for achieving
the objectives. It constitutes the blue print for the collection, measurement and analysis of data. It
is the plan, structure and strategy of investigation conceived so as to obtain answers to research
questions. Aresearch design is the program that guides the investigator in the process of collecting,
analyzing and interpreting observations.
Needs of Research Design
a. Many a research enquiry, the researcher has no idea as to how accurate the results of his /her
study ought to be useful, where such in the case, the researcher has to determine how much
inaccuracy may be tolerated.
b. In many research projects, the time consumed in trying to ascertain what the data mean after
they have been collected is much greater than the time taken to design research which yields data
whose meaning is known as they are collected.
c. The idealized design is concerned with specifying the optimum research procedure that could
be followed were there no practical restrictions.
Characteristics of a Good Research Design
a. It is a series of guide post to keep one going in the right direction.
b. It reduces wastage of time and cost.
c. It encourages co-ordination and effective organization.
d. It is a tentative plan which undergo modifications, as circumstances demand, when the study
progresses, new aspects, new conditions, and new relationships come to light and insight into the
study deepens.
e. It has to be geared to the availability of data and the cooperation of the informants.
f. It has also to be kept within the manageable limits.

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Components of Research Design
It is important to be familiar with the important concepts relating to research design. They are:
1. Dependent and Independent variables: A magnitude that varies is known as variable. When
changes in one variable depends upon the changes in one or more other variables, it is
known as a dependent or endogenous variable, and the variables that cause the changes in
the dependent variable are known as the independent or exogenous variables.
2. Extraneous variable: The independent variable which are not directly associated to the
purpose but effect the dependent variable are known as extraneous variable.
3. Control: One of the most important features of a good research design is to minimize the
effect of extraneous variable. Technically, the term control is used when a researcher
designs the study in such a manner that it minimizes the effect of extraneous independent
variables. The term control is used in experimental research to reflect the restrain in
experimental conditions.
4. Confounded relationship: The relationship between dependent and independent variables
is said to be confounded by an extraneous variable, when the dependent variable is not
from its effect.
5. Research hypothesis: It is the predictive statement which relates a dependent variable and
an independent variable.
6. Control group: In experimental research, the group which is exposed to usual condition is
known as control group.
7. Experimental group: The group which is either receive or exposed to the intervention is
called experimental group.
8. Treatment: It is referred to the different condition to which the experimental and control
group is subjected to.
Different type of research design:
1. Experimental Research Design: It is the most scientifically sophisticated research
method. Experimental research designs are concerned with examination of the effect of
the independent variable on the dependent variable, where the independent variable is

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manipulated through treatment or intervention, and the effect of these interventions is
observed on the dependent variable. It is the process of carrying out research in an
objective and controlled fashion so that precision is maximized and specific conclusions
can be drawn regarding a hypothesis statement. Generally, the purpose is to establish the
effect that a factor or independent variable has on a dependent variable.
Three main characteristics of experimental research design:
a. Manipulation: It refers to a conscious control of the independent variable by the
researcher through treatment or intervention to observe its effect on the dependent
variable. The process by which researchers purposefully change, alter, or influence the
independent variables (IVs), which are also called treatment variables or factors,
b. Randomization: Randomization in an experiment refers to a random assignment of
participants to the treatment in an experiment. It means that every subject has an equal
chance of being assigned to the experimental or control group. It is used in true
experimental research designs to minimize the threat of internal validity of the study
and to eliminate the effect of extraneous variables on dependent variables.
c. Control: It is another essential element of a true experimental design. It refers to the
use of a control group and controlling the effects of extraneous variables on the
dependent variable in which the researcher is interested. The Control groups are
essential to experimental design, When, researchers are interested in the impact of a
new treatment.
The control group could be of the following three types:
• Negative control: In this type of control group, the subject receives neither a
placebo nor any other type of treatment or intervention.
• Clear control: The subjects in this type of control group receive a placebo.
• Positive control: The subjects in the control group receive other treatment or
experimental intervention.
2. Observational Research Design:
It is also known as epidemiological or noninterventional or nonexperimental
research design. It is one of the broad categories of research designs in which the
researcher observes the phenomena as they occur naturally and no external
variables are introduced. It is a research design in which neither the variables are

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deliberately manipulated nor the setting is controlled. The observational design is
subdivided into descriptive, including cross-sectional, case report or case series,
and correlational, and analytic which includes cross-section, case-control, and
cohort studies.
I. Descriptive Research Design: The purpose of descriptive studies is to observe,
describe and document aspects of a situation as it naturally occurs, and sometimes to
serve as a starting point for hypothesis generation or theory development.
II. Cross-sectional: In a cross-sectional study, the investigator measures the outcome and
the exposures in the study participants at the same time.
III. Case Report: A case report is a detailed report of the symptoms, signs, diagnosis
treatment, and follow-up of an individual patient.
IV. Case Series: A group or series of case reports involving patients who were given
similar treatment.
V. Correlational: A correlational research design investigates relationships between
variables without the researcher controlling or manipulating any of them.
VI. Analytical Research: It is a specific type of research that involves critical thinking
skills and, the evaluation of facts and information relative to the research being
conducted.
VII. Case-control: In a case-control study, participants are selected for the study based on
their outcome status. Thus, some participants have the outcome of interest (referred to
as cases), whereas others do not have the outcome of interest (referred to as controls).
The investigator then assesses the exposure in both these groups.
VIII. Cohort Study: is a type of nonexperimental or observational study design. In a cohort
study, the participants do not have the outcome of interest to begin with. They are
selected based on the exposure status of the individual. They are then followed over
time to evaluate for the occurrence of the outcome of interest.
3. Diagnostic Research Design: This research design seeks to identify the underlying cause
of a certain condition or phenomenon. It is used to evaluate the frequency with which
something occurs and its interaction with other element.
4. Exploratory Research Design: It is a methodology approach that investigates research
questions that have not previously been studied in depth.

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SAMPLING
Introduction: A part of the population is known as sample. Sampling is a process of selecting
representative units from an entire population of a study. The target population is the total group
of individuals from which the sample might be drawn. Sampling helps in time and cost saving.
Purpose of sampling:
Economical: With the help of sampling, the researcher can save lots of time, money and resources
to study a phenomenon. Therefore, sampling provides an economical option for the researcher to
generate empirical evidences.
Improve quality of data: It is proven fact that when a person handles less amount of work or less
number of people, it is easier to ensure the quality of the outcome.
Quick study result: Studying an entire population itself will take a lot of time, and generating
research results of a large mas swill be almost impossible as most research studies have time limits.
But with a sample, it is possible to generate study results fast, which is one of the important
objectives of every researcher.
Advantage of sampling
➢ Limit the number of units for study. (Unit– the object whose characteristics are studied)
➢ It makes study feasible in respect of budget, time and logistics.

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Characteristics of a good sample
➢ Representativeness: A representative sample is that whose key characteristics are closely
related to those of the population. Representativeness of a sample makes it possible to generalize
the findings for the population. A sample must be representative of the population.
➢ Accuracy: an accurate sample is one which exactly represents the population.
➢ Precision: Precision is measured by standard error. The sample should be free from simple
random sampling errors or sampling bias.
➢ Size: a good sample must be adequate in size in order to be reliable.
Types of sampling: There are two generic types
A) Random or probability sampling
B) Non-Random or Non-probability sampling
A) Random or probability sampling: It is based on theory of probability. It provides a known
non-zero chance of selection for each population element. In this every subject in a population has
equal chance to be selected as a study sample. In probability sampling techniques, the chances of
systemic bias are relatively less because subjects are randomly selected. There are four methods
of random sampling.
1. Simple random sampling
2. Systematic random sampling
3. Stratified random sampling
4. Cluster sampling

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1.Simple random sampling: This sampling technique gives each element an equal and
independent chance of being selected.
➢ Drawing sample numbers by using (a) lottery method, (b)a tables of random numbers or (c) by
using computer.
➢ This type of sampling is suited for a small homogeneous population.
➢ This is one of the easiest methods.
2. Systematic random sampling: In this sampling, elements are selected from the population at
a uniform interval that is measured in time, order, or space. It is simpler than random sampling.
3.Stratified random sampling: In this method we divide the population into relatively
homogeneous groups, called strata. Then we use one of the two approaches- Either we select at
random from each stratum a specified number of elements corresponding to the proportion of that
stratum in the population as a whole or we draw an equal number of elements from each stratum
and give weight to the results according to the stratum’s proportion of total population. Hence there
are two method of sampling – 1. Equal allocation and 2. Proportional allocation
4.Cluster sampling: In this method we divide the population into the group or clusters, and then
select a random sample of these clusters. We assume that these individual clusters are
representative of the population as a whole. A well-designed cluster sampling procedure can
produce a more precise sample at considerably less cost than that of simple random sampling.
➢ Needs of randomization: The process of assigning the study subjects randomly to either the
treatment or control group is called randomization.
• It is essential to control various known or even unknown biases at the beginning of the
trial and during the course of trial. It is very helpful in achieving this objective.
• Randomization always remove the bias influencing the result.

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• Randomization allows for valid statistical interpretation of raw data.
• It eliminates selection bias.
• It avoids systemic difference between groups.
• It produces comparable group.
B) Non-Random or Non probability sampling: It is not based on the theory of probability. This
sampling does not provide a chance of selection to each population element. This method of
sampling is simple, convenience and low cost.it may be classified into –
1. Convenience or accidental sampling: It means selecting sample units in a just “hit and miss”
fashion. It the cheapest, simplest and not require any statistical expertise. But this is highly biased
because of researcher’s subjectivity.
2. Purposive or judgmental sampling: This method means deliberate selection of sample units
that conform to some predetermined criteria. It may not be true representative of their parent
population.
3. Quota sampling: This is a form of convenient sampling involving selection of quota groups of
accessible sampling units by traits such as sex, age, social class. Etc.
4. Snow-ball sampling: This is a method of building up a list or a sample of a special population
by using an initial set of its members as informants.it is useful for smaller population for which no
frame is readily available.