Classification and Types of Research Designs

2/18/2014 2www.drjayeshpatidar.blogspot.com

CLASSIFICATION OF RESEARCH DESIGN (POLIT & HUNGLER, 1999)

ESSENTIAL CHARACTERISTICS OF EXPERIMENTAL
DESIGNS
Randomization
Control Manipulation
Experimental
Design

RANDOMIZATION
Participants being assigned to either
receive (experimental group) or not
receive (control group), the
treatment condition or intervention
(IV).

METHOD OF RANDOMIZATION
•Lottery method
•Tossing a coin
•Random number table
•Computer

MANIPULATION
Manipulation is the process of
maneuvering the IV, so that its effect
on the dependent variable (D.V) can
be observed/measured.

METHOD OF MANIPULATION
Researcher gives intervention to
experimental group and withholds it to the
control group or administers some other
treatment. E.g. Gentle message is effective
as a pain relief measures for elderly.

CONTROL
Control is for elimination of bias.
Control group refers to a group of
subjects, whose performance is
used to evaluate the performance
of experimental group on same
D.V.

Eg. Effect of nutrient diet on the
weight of premature infant in two
weeks.
Comparison of post intervention
weight with pre-intervention
weight determines the
effectiveness of nutrient diet.
CONTROL

The type of experimental design is
determined by the amount of
control the researcher is able to
exercise over the research condition.
CONTROL

1. TRUE EXPERIMENTAL DESIGN
1.1 Classic experimental design/pretest-post
test control group design
R O1 x O2 (Experimental group)
R O1 O2 (Control group)

Experimental
Group- E
Pre test Treatment (X) Post test (x)
Control group-
C
Pre test Post test (y)
Example
•Tepid sponge (IDV) --> reduction of temperature (DV)
•Paracetomol (IDV) --> reduction of temperature (DV)
COLLECT PRETEST DATA BEFORE RANDOMIZATIONTWO GROUPS
Example of Pre test – Post test Design.

Example of True Experimental Study
Sneha, “Effectiveness of massage on the
selected physiological variables of low
birth weight infants”. In NICU of Bharati
Hospital, Pune, 2010.

1.2 Post test only
control group design
R X O1 (Experimental group)
R O1 (Control group)

Experimental group E Intervention
introduced
X
Level of phenomenon
after intervention (Y)
Control group C Level of phenomenon
without intervention (Z)
Intervention Effect =(Y)-(Z)
Example of Post-Test only Control Group Design

Example of Post Test only Control
Group Design
Vijayakumari G: A study to assess the
effectiveness of structured teaching
program regarding nature and prevention of
accidents among mothers of toddlers in
selected areas of Raichur (2004).

2. QUASI-EXPERIMENTAL DESIGNS
A quasi experimental design is one in
which experimental and control
(comparison) are present &
randomization is not there.
Ex. Effect of primary Nursing education
on staff morale.

2.1 Non equivalent control
group design
R O1 X O2
R O 3 O4
Effect = (O2 – O1) – (O4 – O3)
R = Randomization.
O = Observation or measurement
X = Treatment or intervention

A researcher might choose a group of patients
with diabetes on one hospital floor for the
experimental group and a group of patients
with diabetes on another floor for the
comparison group. The experimental
treatment would be administered to the
experimental group; the comparison group
would receive no treatment or some alternative
treatment.

E.g. A non-equivalent control group design
was used by Valliammal Sudhakar (2008) to
study the knowledge, attitude and practice
towards physical well being of a group of
IV, V, VIth grade students in two different
schools.

2.2 THE TIME SERIES DESIGN
• The time series design, a single group
experiment comprises of series of
observation in the before-time period to
establish a baseline.
• The experimental independent variable is
then introduced,
• Followed by another series of observation to
examine the effect of the independent
variable.

2.2.1 Time series Design (single group)
Before x After
………...……………………………………...
E O1 O2 O3 O4 O5 x O6 O7 O8 O9 10
………………………………………………

2.2.2 The Multiple Time Series Design
Time series non equivalent control group design
(QED)
Before x After
………………………………………………………..
E O1 O2 O3 O4 O5 x O6 O7 O8 O9 10
………………………………………………………………………………………
C O1 O2 O3 O4 O5 - O6 O7 O8 O9 10
……………………………………………………………………………

A researcher might assess the pain levels
of a group of patients with low back pain.
After 3 weeks of pain assessment, intervention
will be introduced
(O1 O2 O3 x O4 O5 O6).
The results of this study would help the
researcher to determine if a specific exercise
is effective in reducing low back pain.

3. PRE EXPERIMENTAL DESIGN
Pre experimental design: are
discussed to provide examples
of how not to do research.

PRE-EXPERIMENTAL DESIGNS:
3.1 The one-shot case study or single case study
In single case study, that studies at once, following a
treatment or an agent presumed to cause change.
Because the study design has a total absence of
control; it is considered to be little value as an
experiment
X----------------O
X= independent variables or stimulus

ONE-SHOT CASE STUDY
Lalitha, Premila & Balu (2006) conducted a
study on nursing personnel registered for a
day workshop on life skill education at
MTIHS, Pondicherry.

3.2 ONE GROUP PRE-TEST AND
POST-TEST DESIGN
• Here only one group is observed before and
after the independent variable is
introduced.
• Loss of the control group decreases the
usefulness of the study but may be
necessary in cases where it is not possible
or feasible to have control groups

E.g. Sailaxmi Gandhi(2006) conducted
a pre-experimental study to assess
the effectiveness of stress
management programme on the
selected variables of nurses working
in psychiatric wards at NIMHANS,
Bangalore.

Non-experimental

CONCLUSION
• Quantitative research approach is the
commonest
• Replication is possible
• Data analysis is easy
• Researcher’s subjectivity is minimal

Classification and Types of Research Designs

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