experimental design techniques

1. Experimental design techniques

2. • The design of fundamental relationship under
controlled situation is called experimental
design.
• Controlling is nothing but holding one variable
constant while other variables are free to vary
within the experiment.
• Independent variables are manipulated in
order to measure their effect on dependent
variable.

3. • An experiment is an observation under
controlled conditions.
• It is a design in which some of the variables
being studied are manipulated to control the
conditions.

4. Types
• Pre –experimental designs
• Quasi-experimental design
• Observational or true experimental
design

5. Pre- experimental designs
• It is the design in which the basic
experimental steps are followed without
assigning any control group.
• The researcher studies a single group with no
any comparison within this group.
• It is a preparatory to true experimental design.
• It is the simplest form of research design.

9. Quasi experimental design
• The study subject are not randomly assigned to
the groups.
• Manipulation of an independent variable.
• It differs from experimental research because
there is no control, random selection and no
active manipulation.
• It is performed when a control group cannot be
created or random selection cannot be
performed.
• It is used in certain medical and paramedical
studies.

13. True experimental design
• It employs statistical analysis to support or
reject a hypothesis.
• It has control group.
• It is the most accurate type of experimental
research it supports or disproves the
hypothesis using statistical analysis
• It is the only design where it cause and effect
the relationship between the variables.

14. True experimental design satisfy the
following
• There must be a control group which wont
change
• An experimental group which will experience
the changed variables.
• There must be a variables that can be
manipulated by researcher.
• There must be a random distribution
• It can be further categorized as

15. Post test only control group design

18. After-only design
• Experimental and control group are similar.
• Uncontrolled factors affect both the groups
casually.
• The experimental group is exposed to
assumed variable but the control group
remains unexposed.
• After experimentation both the groups are
compared there is some effect produced in
the experimental group

19. • The control group assumed to e exactly same
but it is not true.

20. Before after desi
• Dependent variables is measured both before
and after the exposure of groups to
experiment.
• It use several group.
• It has one or more control group.
• Major weakness is a group is influenced by the
external factors .
• It is more reliable than after- only d

21. Ex-post design
• Researcher depend on historical background t,
because sometimes it is not possible to divide
the population into two clear and similar
group.
• It is necessary to study the entire historical
background.
• The past is studied through the present.

22. Panel study designs
• Method of study of a particular subject over time
by using different kinds of data.
• The researcher secure direct evidences of time
dependent relationship among variables.
• It involves repeated observations on the same
subject at different period of time is known as
time-series study.
• It is continuous , deep and reliable design
• It has limitation such as loss of panel member
absenteeism and rigid attitude of members.

23. Post -test only design
• It has two randomly assigned groups.
• Experimental group and control group.
• The treatment is applied to experimental
group.
• The post-test is conducted on both the group
to measure the effects of the treatment.
• When pretesting is not possible or not
required this design is commonly used.

24. Pre test post test only design
• In this design experimental and control group
are formed
• They are pretested for independent variable.
• During experiment only experimental group
receives the treatment.
• Finally both the groups are post tested to
investigate the effects of the independent
variable on the dependent one.

25. Solomon four group design
• Four groups randomly formed.
• Two experimental and two control group.
• One pre tested and one un pretested group
receives the treatment.
• All four group receives the post test.
• Post test result demonstrate the effect of the
dependent variable comparing to the effect of
the independent variable on the dependent
variable.
• It is used to eliminate potential source of error.

26. Factorial design
• In this design two or more independent
variable are simultaneously manipulated to
observe their effects on the dependent
variable.
• It is useful to the researcher to test two or
more hypothesis in a single experiment.
• The independent variables in this design are
called as factors.

27. • Subdivision of factors is called a levels.
• It helps the researcher to investigate the
individual effect of each treatment on the
dependent variables as well as their joint
effect.

28. Randomised block design
• Subject population is grouped into relatively
homogenous subgroups [ blocks] within which
the experiment is replicated
• It is used when there is inherent difference
between subjects and possible differences in
experimental conditions.
• If there are a large number of experimental group
the randomised block design is used because this
design make the group homogenous.

29. • It is used when need to reduce the noise or
variance in data.
• The noise may be attributed to the differences
between the blocks .
• This design helps to detect and examine actual
effects of interest much more accurately.

30. Cross over design
• Different orders of treatment is randomly
assigned to the subjects.
• It is also known as repeat measures design.
• The groups for comparison need to have an
equal distribution as well as there should be
high level of similarity among the subjects.
• The subject in this design serve as their own
control

31. • Limitation is subjects exposed to first treatment
may effect their responses to second treatment.
• Experimental research is aimed to draw
conclusions by controlling the external factors in
order to provide definite conclusions about the
effect of the independent variables on the
dependent variables.
• The purpose of experimental research design is to
test the hypotheses of a fundamental relationship
between variables.