The success or failure of an investigation usually
depends on the design of the experiment.
Prepared by
Odyssa NRM Molo
A description of what a
researcher would like to find out
and how to find it out.
 The background information can
be used as a guide.

•
•
•
•
Complete sequence of steps or procedures that
need to be followed when obtaining the needed
data during investigation.
Serves as a guide during the actual
experimentation.
Minimizes the cost of experimentation while
maximizing the gathered info relevant to the
problem.
Validates the statistical test.






Subject of the study
Variables
Controls
Experimental & control groups
Instruments & devices to be used
Statistical tools needed for analysis
•
•
•
•
Main material being used in the experiment
Also called experimental unit
Can be a person, an animal, a plot in a field, a
plant, a leaf or a model of a device.
Can be subjected to different treatments
depending upon the objectives of the study
–
Treatment denotes any procedure done on the
experimental unit which will then be measured &
analyzed.




Replication
Randomization
Local control
Control of extraneous variables
Experiment should be repeated several
times to find an estimate of variations
among observations on the groups of
subjects treated alike.
– Allows the researcher to assess the
significance of the observed differences
–
Refers to the assignment of the
experimental subjects to the treatments
by chance.
– It is done to create equivalent groups
prior to experiments; average out
differences among groups; reduces
possible bias; assures valid estimate of
population parameters & statistical test
of significance
–

Done when balancing, grouping and
blocking of experimental units are
employed in adopted design.

Identical conditions must be provided for
the control & experimental groups. These
2 groups should differ only in terms of
the absence (control) or presence of the
treatment (experimental)


Completely Randomized Design
(CRD)
Randomized Complete Block Design
(RCBD)
•
•
•
Treatments are assigned randomly to the
experimental subjects without restriction.
Experimental subjects should be homogenous
with respect to all other factors which could
affect the treatment being compared if they
were not controlled.
Used specially for experiments with
homogenous experimental units or in
experiments where environment effects are
easily controlled .
•
•
•
Divides the experimental subjects into more or
less homogenous groups called blocks.
Blocking is done to make sure that the
experimental subjects in a group have similar
characteristics so that observed differences
among the groups will be largely due to the
treatments.
Most appropriate to use if subject can be
categorized according to certain characteristics
like gender, age, weight, & height that can
affect comparison of treatments
Ready for quiz????
Yeah!!!
1)
2)
3)
4)
5)
A description of what a researcher would like
to find out and how to find out.
A complete sequence of steps or procedures
that need to be followed when obtaining the
needed data during an investigation.
The main material being used in the
experiment.
Any procedure done on # 3 answer.
Assignment of experimental subjects to the
treatment by chance.
6) Done when balancing, grouping & blocking of
experimental units are employed in the
adopted design.
7) Treatments are assigned randomly in this
design.
8) Homogeneous groups
9) Design where subjects are divided in groups
10) Group where treatment is absent.
11-14 Principles always present in a research design
15 – 16 Types of research design
True or False
17) CRD is characterized by blocks of equal size.
18) RCBD is appropriate for use if the subjects have
the same characteristics.
19) Design of an experiment depends on the type of
research being undertaken.
20) Research designs minimizes cost while gaining
maximum information relevant to the problem.

Page 33, Study Guide # 2
Identify the subject/s
 Identify the treatment
 Identify the control group/s
 Identify the experimental group/s
 Identify the dependent, independent, & extraneous
variables



Caintic, Helen E and Juanita M. Cruz. (2008)
Scientific Research Manual. C&E Publishing,
Inc.
Brynie, Faith Hickman. (1998) Painless Science
Projects. Barron’s Educational Series, Inc.