data collection -experiment design for class2003

8/6/2019 Data Collection -Experiment Design for Class2003

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Business

Research Methods

Experimental Research


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Experiment

A research investigation in which conditions are

controlled

One independent variable is manipulated

(sometimes more than one)

Its effect on a dependent variable is measured

To test a hypothesis


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Nature of experiments

Purpose: Control the research situation so

that causal relation ship among variables can

be evaluated

E.g. impact of training on performance

Impact of store atmospherics on the sales / footfall

Impact of sales promotion on sales


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Why experimental studies

Survey/ observation method might not result

truthful result

It may not be socially desirable to therespondents to admit

Unwilling to provide truthful response

Interviewers bias, error in questionnaire,misunderstanding of the question and so on

might cause errors


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A Classification of Experimental Designs

Pre-experimental

One-Shot Case

Study

One GroupPretest-Posttest

Static Group

True

Experimental

Pretest-Posttest

Control Group

Posttest: OnlyControl Group

Solomon Four-

Group

Quasi

Experimental

Time Series

Multiple Time

Series

Statistical

Randomized

Blocks

Latin Square

Factorial

Design

Experimental Designs

These designs are discussed while dealing research design . Read the text 273These designs are discussed while dealing research design . Read the text 273 287287


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Four Basic Issues of Experimental Design

1.Manipulation of the Independent Variable

Independent variable as Classificatory Vs. continuous variables

Experimental and control groups

Treatment levels- knowing what is enough

More than one independent variable-( e.g. increase ads and price reduction

together)

2. Selection & Measurement of Dependent ( criterion) Variable

For a given independent variable, chances of many dependent variable

Time span with in which dependent variable should be measured &

Depends on Management Decision and Research Question


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Four Basic Issues of Experimental Design

3. Selection & Assignment of Subjects (or other Test Units)

Test units : are the respondents

Constant (systematic )/and random sampling error so random assignment

Randomization control by chance i.e. groups are identical except the

treatment

Matching matching elements on pertinent characteristics

Repeat measures- using the same subjects to avoid subjects difference

4.Control Over Extraneous Variables

Constant experimental error systematic error

Extraneous variable- must be controlled or eliminated

Demand characteristics designing experiment that gives hint to subjects

about hypothesis experimenters bias guinea pig effect/ Hawthorne effect

Establishing control ( or constancy) on major external factors eg head and

shoulder shampoo test experiment- no identification , order presentation &

counter balancing, blinding

Problems controlling extraneous variables due to competitors, management

etc.,


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Fundamental questions in experimentation

Basic vs. factorial experimental design

Basic experimental design-single independent variable

is manipulated to measure impact on single dependent

variable

Factorial experimental design -Simultaneous change of

two or more independent variables measuringinteraction of 2 or more independent variables to

measure sophisticated dependent variable Impact of ad and price on sales


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Laboratory Experiment Field Experiment

Artificial-Low Realism

Few Extraneous

Variables

High control

Low Cost

Short Duration

Subjects Aware of

Participation

Natural-High Realism

Many Extraneous

Variables

Low control

High Cost

Long Duration

Subjects Unaware of

Participation

Field Vs. Laboratory Experiment


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Issues of experimental validity


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Experiment Validity

Experiments are judged by two measure internal and external

validity

When does an Experiment have Validity?

Internal Validity ( cause &effect relationship) indicates whetherthe experimental treatment was the sole cause of changes in a

dependent variable

Did the manipulation do what it was supposed to do?

If the results are confounded by extraneous factors concludingthe relationship between IV & DV dificult

External validity-extent to which the results of the experiment are

applicable in the real world


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Factors Influencing Internal Validity

HistoryHistory-- specific event in environment occurring between first and second

measurement & which is beyond the control of experimenter and affect the validityof experiment-lock out or strike in organization, fall in stock market , change ineconomic condition Cohort effect is special case of history effect . Change in dependent variable occurs as one group

experience different history in the environment

MaturationMaturation-- effect on result due to changes in the subjects over time Function of time. s subjects may feel hungry, bored, tired, grow old or more experienced

Eg. selling skill training for long period

TestingTesting (pretesting effect) happens in pretest and post test design Exposure to pre test might sensit ize respondents to respond differently than if they or not exposed

InstrumentationInstrumentation-- effect on result an experiment caused by change themeasurement instrument- questionnaire/ test

Change in wording, interviewer or change in procedure to measure dependent variable

SelectionSelection-- sample selection error, differential selection of respondents forcomparison groups

MortalityMortality-- sample attrition when more subjects withdraw from experiment ( fromexperiment group) before completion& thus affecting the validity of theexperiment

Predicting employee turn over project Completion of training and closer supervision


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External validity

Quality of being able to generalize the result to

the external environment/ population E.g. generalizing result of simulated experiment to real world

of retail

Generalization of test commercial result on actual ads

Students Surrogates- students sample may notprovide an accurate prediction of otherpopulations

Trade offs- trade off internal validity for externalvalidity- field experiment have less internal validitybut greater external validity

You can not create experience but you must undergo itYou can not create experience but you must undergo it

Albert CamusAlbert Camus


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How can Internal Validity Increase?


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Increasing Internal Validity Control group

Random assignment

Pretesting and posttesting

Posttest only

data collection -experiment design for class2003

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