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Chapter-4

EXPERMENTATION

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Contents

Issues in experimentation

Experimental designs

Experimental environment

Types of experimental designs

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EXPERIMENTATION

An experiment refers to the process ofmanipulating one or more variables andmeasuring their effect on one or more

variables, while controlling the externalvariables. The variable, which ismanipulated , is called the independentvariable and the variable whose behavior

is to be measured in the experiment iscalled dependent variable.

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Contd..

A well executed experiment can depict thecausal relationship between variables

by controlling extraneous variables.

To conduct experiments successfully,researchers have to consider certainaspects which include treatment,

experimental groups and control ofextraneous variables.

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ISSUES IN EXPERIMENTATION

There are four key issues a researcher

has to consider while conducting an

experiment.

Treatment of independent variables

Experimental groups and control groups

Selection and measurement of thedependent variable

Control of extraneous variables

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Experimental Validity

Validity is the extent to which a researchprocess is accurate and reflects actual

market conditions. There are two types of

validity which are considered inexperimentation.

Internal validity

External validity

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Internal Validity

Internal validity measures to what extentthe change in a dependent variable can beexplained by the independent variable.

Internal validity refers to theapproximate validity with which we inferthat a relationship between two variablesis causal or that absence of a relationship

implies the absence of cause.

contd..

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Contd..

The influence of extraneous variables should beincluded to improve the experiments internalvalidity. The following are seven major types ofextraneous variables that are sources of threat tointernal validity.

History Maturation

Testing

Instrumentation

Selection bias Statistical regression

Mortality

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External Validity

External validity measures to what extent the

inferences derived from experiments can be

generalized to the real environment.

External validity refers to the theapproximate validity with which we can infer that

the presumed causal relationship can be

generalized to and across alternate measures of

the cause and effect and across different typesof persons, settings, and times

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Experimental Environment

Experiments are conducted in:

Laboratory Environment

Field EnvironmentThe first one means the experiment is

conducted under artificial conditions.

The second one refers to conducting anexperiment in real conditions.

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Types of Experimental Designs

The experimental designs are classified intofour categories:

Pre-Experimental Designs

True Experimental Designs

Quasi-Experimental Designs

Statistical Designs

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Pre-Experimental Designs

Pre-experimental designs lack propercontrol mechanisms to deal with theinfluence of extraneous variables onexperimental results.

There are three prominent pre-experimental designs used by businessresearchers:

One-shot design (after only design) One-group pre-test-post-test design

Static group design

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True Experimental Design

True experimental designs userandomization to control the influence ofextraneous variables.

The following are prominent trueexperimental designs widely used inbusiness research:

Pre-test-post-test control group design Post-test-only control group design

Solomon four group design

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Quasi-experimental Designs

Quasi-experimental designs are used

when it is not possible to assign test

units randomly to experimental

treatments or assign experimental

treatment randomly to test units.

Prominent quasi-experimental design

used by researches is:

Time-series designs

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Statistical Designs aid in measuring the effect ofmore than one independent variable.

They help in isolating the effects of mostextraneous variables, thereby providing better

experimental results.

Four prominent experimental designs are:

Completely randomized design

Randomized block design Latin square design

Factorial design

Statistical Designs

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