2.
Introduction:
A research design is the frame work or guide used for the
planning, implementation, and analysis of a study. It is a
systematic plan of what is to be done, how it will be done,
how the data will be analyzed.
Research design basically provides an outline of how the
research will be carried out and methods that will be used.
It is, in other words, a master plan for executing a research
project.
Research design
3.
The purpose of a research design is to provide a plan of
study that permits accurate assessment of cause and effect
relationships between independent and dependent
variables. The classic controlled experiment is an ideal
example of good research design.
Purpose
4.
Variables
• This variable is the “cause”/ as the predictor
variable.
Independent
variable
• This variable is the “effect”/ should vary only
in the response of independent variable/ also
known as criteria variable.
Dependent
variable
• Independent variables that are not related to the
purpose of study, but may affect the dependent
variable. whatever effect is noticed on dependent
variable as a result of extraneous variable is
termed as ‘experimental error’.
Extraneous
variables
Confounding
variables
• When the dependent variable is not free from the
influence of extraneous variable the relationship
between dependent and independent variable is said
to be confounded by an extraneous variable.
6.
Experimental research is a scientific approach to research,
where one or more independent variables are manipulated
and applied to one or more dependent variables to measure
their effect.
Experimental research involves a direct assessment of how
one variable influences other.
It is defined as “observation under controlled condition”.
It is most scientifically sophisticated research method.
Experimental research
8.
Experimental studies are those where the researcher tests the
hypotheses of causal relationships between variables.
Professor R.A. Fisher’s name is associated with experimental designs.
Beginning of such designs was made by him when he was working at
Centre for Agricultural Research in England.
Professor Fisher found that by dividing agricultural fields or plots into
different blocks and then by conducting experiments in each of these
blocks, whatever information is collected and inferences drawn from
them, happens to be more reliable.
Since experimental designs originated in the context of agricultural
operations, we still use, though in a technical sense, several
terms of agriculture (such as treatment, yield, plot, block etc) in
experimental designs.
History of experimental design
10.
Randomization means that every subject has an equal chance
of being assigned to the experiment. Through random
assignment of subject under experimental or control group,
chances of systemic bias is eliminated.
Randomization is used in true experimental research design to
minimize the treat of internal validity of the study and to
eliminate the effect of extraneous variables on dependent
variables.
RANDOMIZATION
11.
Methods used for randomization are:
Lottery method/Slip of paper
Flip a coin/Tossing a coin
Random table
12.
Manipulation is the process of maneuvering the intervention
(Teaching programme, Pamphlet & Brochures) so that the effect
on the dependent variable can be observed/measured.
It refers to conscious control of the independent variable by the
researcher through treatment or intervention to observe its effect
on the dependent variable.
MANIPULATION
13.
Control refers to the use of control group and controlling the
effects of extraneous variables on the dependent variable in
which the researcher is interested.
It refers to a group of subjects whose performance is used to
evaluate the performance of experimental group.
The subject in the control and experimental groups are
similar in number & characteristics but the subjects in the
control group do not receive experimental treatment or any
intervention at all.
CONTROL
17.
The true experimental research design relies on statistical
analysis to approve or disprove a hypothesis. It is the most
accurate type of experimental design and may be carried
out with or without a pretest on at least 2 randomly
assigned dependent subjects.
The true experimental research design must contain a
control group, a variable that can be manipulated by the
researcher, and the distribution must be random.
True experimental design
19.
Composed of two randomly assigned group, i.e.
experimental and control , but neither of which
is pretested before the implementation of
treatment on the experimental group.
In addition, while the treatment is implement on
the experimental group only, post-test
observation is carried out on both the group to
assess the effect of manipulation.
Post-test only group design
21.
In these experiment the researcher conducts experimental group and
control group.
The effect of the dependent variable on both the groups is seen before
the treatment (pretest).
Later, the treatment is carried out on experimental group only, & after-
treatment observation of dependent variable is made on both the groups
to examine the effect of the manipulation of independent variable on
dependent variable.
For example, such a design could be used for ‘an experimental study to
assess the effectiveness of cognitive behavioral therapy interventions for
patients with breast cancer.
Pre test post-test only design
23.
There are two experimental groups (experimental group1 &
experimental group2) & two control groups (control group1 & control
group2).
Initially, the investigator randomly assigns subjects to the four groups.
Out of the four groups, only experimental group1 & control group1
receives the pretest, followed by the treatment to the experimental
group1 & experimental group2.
Finally, all the four groups receive post-test, where the effects of the
dependent variables of the study are observed & comparison is made of
the four groups to assess the effect of independent variable
(experimental treatment) on the dependent variable.
Solomon 4 group design
25.
In factorial design, researcher manipulates two or more
independent variables simultaneously to observe their effects on
the dependent variables. This design is useful when there are
more than two independent variables, called factors to be tested.
This design also facilitates the testing of several hypothesis at a
single time.
Typical factorial design incorporates 2*2 or 2*3 factorial, but it
can be in any combination.
Factorial design
26.
Frequency of mouth
care
Protocols of mouth care
Chlorhexidine(𝛼1) Saline(𝛼2)
4 hourly(𝛽1) 𝛼1….𝛽1 𝛼2…. 𝛽1
6 hourly(𝛽2) 𝛼1…. 𝛽2 𝛼2…. 𝛽2
8 hourly(𝛽3) 𝛼1…. 𝛽3 𝛼2….. 𝛽3
Factorial design
The first number (𝛼) refers to the independent variables or the
type of experimental treatments, & the second number (𝛽) refers
to the level or frequency of the treatment.
27.
Control of inherent differences between experimental subjects &
differences in experimental conditions is one of the difficult
problems faced by researcher in biological sciences.
When there are a large number of experimental comparison
groups, the randomized block design is used to bring
homogeneity among selected different groups.
For example, a researcher wants to examine the effects of three
different antihypertensive drugs on patients with hypertension.
Randomized block design
28. Types of
antihypertensive
drugs
Blocks
Patient with
primary
hypertension(I)
Diabetic patient
with
hypertension(II)
Renal patient
with
hypertension(III)
A A,I A,II A,III
B B,I B,II B,III
C C,I C,II C,III
In this example, to ensure the homogeneity among the
subjects under treatment, researcher randomly places
the subjects in homogeneous groups (blocks) like
patients with primary hypertension, diabetic patients
with hypertension, & renal patients with hypertension .
29.
In this design, subjects are exposed to more than one treatment,
where subjects are randomly assigned to different orders of
treatment.
It is also known as ‘repeated measures design’.
This design is more efficient in establishing the highest possible
similarity among subjects exposed to different conditions, where
groups compared obviously have equal distribution of
characteristics.
Though crossover design is considered as an extremely powerful
research design, sometimes it is not effective because when
subjects are exposed to two different conditions, their responses of
the second condition may be influenced by their experience in the
first condition.
Crossover design
30.
For example, when we are comparing the effectiveness of
the chlorhexidine mouth care protocol on group I & saline
mouth care protocol on the subjects of group II.
Later, the treatment is swapped, where group I receives the
saline mouth care & group II receives chlorhexidine. In
such studies, subjects serve as their own control.
Crossover design
groups Protocols of mouth care
Group I Chlorhexidine (𝛼1) Saline (𝛼2)
Group II Saline(𝛼2) Chlorhexidine(𝛼1 )
32.
Experimental research designs are considered the most powerful designs
to establish the causal relationship between independent & dependent
variables.
Where the purpose of research is explanation, causal relationship may be
established among the variables by experimentation, especially in studies
involving physical objects, where the variables are more easily controlled
than in human studies.
In this studies, the controlled environment in which the study is conducted
can yield a greater degree of purity in observation.
When the experiment is conducted in a laboratory, experimental unit, or
other specialized research setting, it is removed from the pressure &
problems of real-life situations & the researcher can pursue his or her
studies in a more leisurely, careful, & concentrated way.
Advantages of true experimental design
34.
“Quasi” Latin word means almost but not really.
Quasi-experimental research design involves the
manipulation of independent variable to observe the effect
on dependent variable, but it lacks at least one of the two
characteristics of the true experimental design;
randomization or a control group.
Quasi-experimental research design
35.
Manipulation of the independent variables to observe the
effects on the dependent variables.
Lack of at least one of the two other essential
characteristics of the true experiment, i.e. random
assignment of subject or a control group.
Quasi-independent variables are used instead of true
independent variables. Where independent variable is not
manipulated in complete controller situations.
Main characteristics
37.
It is also known as the ‘nonequivalent control group
design’.
This design is identical to the pretest-posttest control
group design, except there is no random assignment of
subjects in experimental & control groups.
In this design, experimental & control groups are selected
without randomization, & dependent variables are
observed in experimental as well as control groups before
the intervention.
Later, the experimental group receives treatment & after
that posttest observation of dependant variables is carried
out for both the groups to assess the effect of treatment on
experiment group.
Non randomized control group design
39.
This design is useful when the experimenter wants to measure
the effects of a treatment over a long period of time.
The experimenter would continue to administer the treatment &
measure the effects a number of times during the course of the
experiment.
Generally it is a single-subject research, in which the researcher
carries out an experiment on an individual or on a small number
of individuals, by alternating between administering & then
withdrawing the treatment to determine the effectiveness of the
intervention.
Time series design
40. Exp.
group
O1 O2 O3 Treatment O5 O6
O4
Time series design
If no change between O1 and O2 or O2 and O3 but a significant
difference between O3 and O4 will be found ,only then it can be said
that the treatment is effective.
41.
Quasi-experimental designs are more frequently used because they
are more practical & feasible to conduct research studies in different
field, where in the absence of a large sample size, randomization &/ or
availability of control groups are not always possible.
This design is more suitable for real-world natural setting than true
experimental research designs.
It allows researchers to evaluate the impact of quasi- independent
variables under naturally occurring conditions.
It may be able to establish casual relationship. Wherein some of the
hypotheses are practically answered through this design only.
Advantages of quasi-experimental design
43.
Pre-experimental research
design
One- shot case
design
One-group pretest-
posttest design
Pre-Experimental Research Design
This research design is considered very weak, because the
researcher has very little control over the experiment.
44.
In this research design, a single experimental group is
exposed to a treatment & observations are made after the
implementation of that treatment.
There is no random assignment of subjects to the
experimental group & no control group at all.
One shot case study
45.
Example: suppose we wish to see if a new textbook
increases student interest in the course (history, science,
statistics, etc.)
One shot case study
Exp.
group
treatment Post-test
46.
A type of pre-experimental design where pre-test and post-test are
taken with intervention but fails to include randomization and
control.
It is the simplest type of pre-experimental design, where only the
experimental group is selected as the study subjects.
A pretest observation of the dependent variables is made before
implementation of the treatment to the selected group, the treatment
is administered, & finally a posttest observation of dependent
variables is carried out to assess the effect of treatment on the group.
One group pre-test post-test design
47.
Example: suppose we want to assess the effects of weekly
counseling sessions on the attitudes of identified bullies in
school.
One group pre-test post-test design
Exp.
group
Pre-
test treatment Post-test
48.
In these static group comparison design there will be two
groups. Give intervention to one group and give post test
to two groups.
Static group comparison design
Exp.
group
Control
group
Post-
test
Post-
test
treatment
No random assignment
comparison
49.
Very simple & convenient to conduct these studies in
natural settings, especially in nursing.
Most suitable design for the beginners in the field of
experimental research.
Advantage of pre- experimental design
50.
Considered a very weak experimental design to establish
casual relationship between independent & dependent
variables, because it controls no threat to internal validity.
It has very little control over the research.
Disadvantage of pre-experimental design
51.
Pre experimental
design
True experimental
design
Quasi experimental
design
Least effective design Most effective design Less satisfactory design
No control group Control group are
present
Control group are
present
Randomization may be
possible
randomization Used when
randomization is not
possible.
Comparison
53.
1. Corlien M. Varkevisser et al, Designing and conducting
health research projects, vol 1,2003 proposal
development and field work- IDRC
2. C. R. Kothari, Research methodology methods and
techniques, second edition
3. Internet
References
55.
RCT (randomized controlled trials) alone are not
sufficient to prevent the bias and get reliable research
results.
Blinding is needed along with randomization for
completely concealing the treatment allocation.
The best results in clinical research are obtained if
the trial is;
Randomized
Controlled
Double blinded
Blinding
56.
Blinding or masking is a procedure in
which one or more parties in a trial are
kept unaware of treatment allocation of
participants.
Definition
57.
Depending upon the type of the trials the following can
be blinded;
Participant being treated.
Clinical staff or investigator administering treatment.
Team collecting outcome data.
Data analyst.
Who can be blinded?
58.
Blinding is an important aspect of any trial done in order
to avoid intentional or unintentional bias during the
execution of a clinical trial.
Bias can affect:
Recruitment
Treatment allocation
Assessments of the patients
Attitudes towards the patients
Care for patients
Objective of the trial
Reliability of trial results
Why is blinding important?
59.
Unblinded or open label trial
Single-blinded trials
Double-blinded trials
Triple blinded trials
Types of blinding
60.
When blinding is not used in a trial, the trial is referred to as
an open trial or unblinded trial.
All the people involved in the trial will be aware of the
treatment group assignment of study participants.
Unblinded trial or open label
62.
A single blinded trial involves blinding of any one group of
individual. Usually, the subjects receiving the intervention,
or the outcome assessors are blinded to the intervention
assignments.
Single-blinded trials
63.
Single-blinded trials used
When double blinding is not possible.
Used when the experimental medicine and
control cannot be manufactured identically.
64.
In a double blinded trial, any two group of individuals are
blinded.
Usually, the investigators as well as the study participants are
blinded to the treatment allocation so, neither the participants
nor the study staff know as to which patient is receiving the
experimental medicine, and which is receiving a placebo or
another therapy.
Double-blinded trials
65.
Double blinding is recommended
in a clinical trials.
Best-controlled trial design.
Decreased chance of observational bias.
Should be used whenever possible.
Advantage of double blinding
66.
Three groups of people are blinded to the
intervention assignments in a triple blinded study.
Usually the subjects, the investigators, and the
outcome assessors are blinded.
Triple blinded trials
67.
Advantage of triple blinding
Increase the accuracy and objectivity of
clinical outcomes.
Helps to avoid bias in the analysis of
results.
68.
Unblinding is the disclosure of the treatment to a
participant or study team.
Generally blinding is broken upon completion of the
trial.
Breaking the blind or unblinding
