3) EXPERIMENTAL DESIGN

8/7/2019 3) EXPERIMENTAL DESIGN

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The aim of the experimental research is to

investigate thepossible cause-and-effect

relationshipby manipulating one independent

variable to influence the other variable(s) in theexperimental group, and by controlling the

other relevant variables, and measuring the

effects of the manipulation by some statisticalmeans. By manipulating the independent

variable, the researcher can see if the treatment

makes a difference on the subjects.


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The PURPOSE, therefore, of

experimental designs is to eliminate

alternative hypotheses.


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Experimental Design - A blueprint of the

procedure that enables the researcher to

test his hypothesis by reaching validconclusions about relationships between

independent and dependent variables. It

refers to the conceptual frameworkwithinwhich the experiment is conducted.


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Single-variable design Pre-experimental designx One-shot case studyx One-group pretest-posttest designx S

tatic group comparison True experimental designx The posttest-only control group designx The pretest-posttest control group designx Solomon four-group design

Quasi-experimental designxNon-equivalent control groups designx Time-series designx Counterbalanced design

Factorial design S

ingle-subject design


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Identify and define the problem. Formulate hypotheses and deduce their consequences. Construct an experimental design that represents all

the elements, conditions, and relations of theconsequences. 1. Select sample of subjects.

2. Group or pair subjects.

3. Identify and control non experimental factors. 4. Select or construct, and validate instruments to measure outcomes.

5. Conduct pilot study. 6. Determine place, time, and duration of the experiment.

Conduct the experiment. Compile raw data and reduce to usable form. Apply an appropriate test of significance.


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Experimental investigations can beconducted on groups orindividuals. Mostoften used animals and human behaviours characteristics of a person or things thancan occur in different amounts or kinds.

In true experimental design, subjectswithin the groups are randomly assignedto program and comparison groups.


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Instrument such as questionnaires,

observations, laboratory treatments, field

experiment results etc. are used.

Apilot study or two is made on some

before doing the real experiment.

Internal and external validation are

usually conducted.


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A randomization tool is used to assignsubjects and treatments of group which isbased on chance.

Experimental design is frequently analyzedwith a two-sample t-test assuming equal

variances of the groups orone-way ANOVAused to test for a difference in means betweentwo groups.


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The aim of an analysis is to draw a conclusion, togetherwith other observations. The researcher might generalizethe results to a wider phenomenon, if there is no

indication ofconfounding variables "polluting" theresults.

The final stage is the researchers recommendationsbased upon the results, depending upon the field ofstudy. This area of the research process can be basedaround the researchers personal opinion, and willintegrate previous studies.

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3) EXPERIMENTAL DESIGN