shaik umme salma,aem MFK-1710,college of fisheries manglore,

1. EXPERIMENTAL
SHAIK.UMME
SALMA
RESEARCH DESIGN

2. • Experimental research is an attempt by the researcher
to maintain control over all factors that may affect the
result of an experiment. In doing this, the researcher
attempts to determine or predict what may occur.
INTRODUCTION

3. • Experimental research design are concerned with examination
of the effect of independent variable on the dependent variable,
where the independent variable is manipulated through
treatment or intervention(s), & the effect of those interventions
is observed on the dependant variable.
EXPERIMENTAL RESEARCH

4. • Describes what will be when certain variables are
carefully controlled or manipulated.
• Objective, systematic, controlled investigation for the
purpose of predicting and controlling phenomena and
examining probability and causality among selected
variables.
EXPERIMENTAL RESEARCH

5. • Experimental research is conducted to determine if
differences result from the interjection of some
phenomenon into peoples’ lives.
• Experimental research always involves intentional
manipulation of one or more variables.

6. • True experimental research means that the researcher
(theoretically) has control over all the relevant variables.
• Experimental research is usually conducted in a laboratory or
other highly controlled settings

7. ESSENTIAL CHARACTERISTICS…
• A true experimental research design must essentially consist of
the following three characteristics:
• Manipulation
• Control
• Randomization

8. CONTROL
• Control is another essential element of true experimental
design.
• Control refers to use of control group & controlling the effects
of extraneous variables on the dependent variable in which
researcher is interested.
• The subject in the control & experimental groups are similar in
number & characteristics, but the subject in the control group
receive no experimental treatment or any intervention at all

9. MANIPULATION
• Manipulation refers to conscious control of the independent
variable by the researcher through treatment or intervention(s)
to observe its effect on the dependent variable.
• In other words, it is a conscious act by the researcher, where he
or she varies the independent variable & observes the effect
that manipulation has on the dependant variable of interest.

10. Experimental researchalsoinvolves
• Comparing conditions under various stages of the
treatment (e.g., Pre-post).
• Systematic manipulation of experimental conditions
in which extraneous influences are controlled or
eliminated.

11. Advantages
– Strength with which causal relationships can be
inferred.
– Ability to manipulate one or more variables.
– Proven to be a very useful and robust scientific
method (i.e., withstood the test of time).

12. Disadvantages
– Tight controls often produce artificial conditions
that could limit the generalizability of the findings.
– Time consuming.
– Expensive.
– Unethical.
– Feasability.

13. TRUE EXPERIEMENTAL DESIGN
POST TEST ONLY
PRE TEST-POST-TEST-ONLY
SOLOMON FOUR-GROUP
DESIGN
RANDOMIZED BLOCK
DESIGN
CROSSOVER DESIGN
FACTORIAL
DESIGN

14. POST TEST ONLY CONTROL DESIGN
•Composed of two randomly assigned group, i.e.
experimental & control, but neither of which is pretested
before the implementation of treatment on the experimental
group.
•In addition, while treatment is implement on the
experimental group only, post-test observation is carried
out on both the group to assess the effect of
manipulation.

15. • This design can be helpful in situations where it is not possible
to pretest the subjects.
• For example, to study the effect of an educational intervention
related to urinary incontinence on the subsequent help-seeking
behavior of older adults.

16. PRETEST-POST-TEST-ONLY DESIGN
• In this research designs, subjects are randomly assigned to
either the experimental pre the 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 dependant variable is made
on both the groups to examine the effect of the manipulation of
independent variable on dependant variable.

17. • 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.’

18. SOLOMON FOUR-GROUP DESIGN
• There are two experimental groups (experimental group 1 &
experimental group 2) & two control groups (control group 1
& control group 2).
• Initially, the investigator randomly assigns subjects to the four
groups.
• Out of the four groups, only experimental group 1 & control
group1 receives the pretest, followed by the treatment to the
experimental group 1 & experimental group 2.

19. • Finally, all the four groups receive post-test, where the effects
of the dependant variables of the study are observed &
comparison is made of the four groups to assess the effect of
independent variable (experimental treatment) on the
dependant variable.

20. • In this, experimental group 2 was observed at one occasion, &
that score should be similar to average scores of those in
experimental & control groups.
• To estimate the amount of change in experimental & control
group 2, the average test scores of experimental & control
groups 1 are used as baseline
• The solomon four-group design is believed to be most
prestigious experimental research design, because it minimizes
the threat to internal & external validity.

21. RANDOMIZED BLOCK DESIGN
• 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.
• This is simple method to reduce the variability among the
treatment groups by a more homogeneous combination of the
subjects through randomized block design.

22. • For example, a researcher wants to examine the effects of
three different antihypertensive drugs on patients with
hypertension.
• 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 hypertention.

23. CROSSOVER DESIGN
• In this design, subjects are exposed to more than onetreatment,
where subjects are randomly assigned to different orders of
treatment.
• It is also known as ‘repeat 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.

24. • Through 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.

25. • 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.

26. FACTORIAL DESIGN
• In factorial design, researcher manipulates two or more
independent variables simultaneously to observe their effects
on the dependant variables.
• This design is useful when there are more than two
independent variables, called factors to be tested.
• For example, a researcher wants to observe the effect of two
different protocols of mouth care on prevention of VAP when
performed at different frequencies in a day.

27. • This design also facilitates the testing of several hypothesis at
a single time.
• Typical factorial design incorporates 2X2 or 2X3 factorial, but
it can be in any combination.
• 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.