Ch12 2

Business
Research Methods

William G. Zikmund

Chapter 12:
Experimental Research

Copyright © 2000 by Harcourt, Inc.

All rights reserved. Requests for
permission to make copies of any part
of the work should be mailed to the
following address: Permissions
Department, Harcourt, Inc., 6277 Sea
Harbor Drive, Orlando, Florida
32887-6777.

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

Copyright © 2000 by Harcourt, Inc. All rights reserved

Basic Issues of Experimental Design

Manipulation of the Independent Variable

Selection of Dependent Variable

Assignment of Subjects (or other Test Units)

Control Over Extraneous Variables


The experimenter has some degree
of control over the independent
variable. The variable is
independent because its value can
be manipulated by the experimenter
to whatever he or she wishes it to
be.


Experiment Treatment

Alternative manipulations of the
independent variable being
investigated


Independent Variable

• The experimenter controls
independent variable.
• The variable’s value can be
manipulated by the
experimenters to whatever they
wish it to be.

MANIPULATION OF INDEPENDENT
VARIABLE

•Classificatory Vs. Continuous Variables
•Experimental and Control Groups
•Treatment Levels
•More Than One Independent Variable


Experimental treatments are
the alternative manipulations
of the independent variable
being investigated.


DEPENDENT VARIABLE

• its value is expected to be
dependent on the
experimenter’s manipulation
• criterion or standard by which
the results are judged


DEPENDENT VARIABLE

• SELECTION
– e.g... sales volume, awareness,
recall
• MEASUREMENT


Dependent Variable

• Selection
- e.g., sales volume, awareness,
recall

• Measurement


The dependent variable is so
called because its value is
expected to be dependent on the
experimenter’s manipulation; it is
the criterion or standard by which
the results are judged.


TEST UNITS - subjects or entities
whose response to the
experimental treatment are
measured or observed.


Two Types of Experimental Error

•Constant Error
•Random Errors


TWO TYPES OF
EXPERIMENTAL ERRORS
• CONSTANT
ERRORS
• RANDOM
ERRORS


FIELD VERSUS LABORATORY
EXPERIMENTS


Controlling Extraneous Variables

• Elimination of Extraneous
Variables
• Constancy of Conditions
• Order of Presentation
• Blinding
• Random Assignment


How May an Experimenter control for
Extraneous Variation?

•Eliminate Extraneous Variables
•Hold Conditions Constant
•Randomization
•Matching Subjects


Establishing Control


DEMAND CHARACTERISTICS

• EXPERIMENTAL PROCEDURES THE
INTENTIONALLY HINT TO SUBJECTS
SOMETHING ABOUT THE
EXPERIMENTER’S HYPOTHESIS


Demand Characteristics

• Guinea Pigs

• Hawthorne Effect


Field Vs. Laboratory Experiment


Laboratory Experiment Field Experiment

Artificial-Low Realism Natural-High Realism

Few Extraneous Many Extraneous
Variables Variables
High control Low control

Low Cost High Cost

Short Duration Long Duration
Subjects Aware of Subjects Unaware of
Participation Participation


CONTROL GROUPS

• Isolates Extraneous Variation


WHEN IS AN EXPERIMENT
INTERNAL VALIDITY?
• INTERNAL VALIDITY - THE ABILITY
OF AN EXPERIMENT TO ANSWER
THE QUESTION OF WHETHER THE
EXPERIMENTAL TREATMENT WAS
THE SOLE CAUSE OF CHANGES IN A
DEPENDENT VARIABLE
• DID THE MANIPULATION DO WHAT
IT WAS SUPPOSED TO DO?

FACTORS INFLUENCING
INTERNAL VALIDITY

• History • Instrumentation

• Maturation • Selection

• Testing • Mortality


ISOLATING EXTRANEOUS VARIATION
WITH A CONTROL GROUP

• History Effects

• Maturation Effects

• Mortality Effects


Type of Extraneous Variable Example

History - specific events in the A Major Employer
Environment between the Before Closes Its Plant in
and After Measurement That Are Test Market Area
beyond the Experimenter’s Control

Maturation - subjects Change Subjects Become
during the Course of the Experiment Tired

Testing - The Before Measure Alerts Questionnaire
or Sensitizes Subject to Nature of about the Traditional
Experiment or Second Measure Role of Women
Triggers Enhanced
Awareness of Women
in an Experiment
Copyright © 2000 by Harcourt, Inc. All rights reserved.

Instrument - Changes in New Questions about
Instrument Result in Response Women are Interpreted
Bias Differently from Earlier
Questions.

Selection - Sample Selection Control Group and
Error Because of Differential Experimental Group Is
Selection Comparison Groups Self-Selected Group
Based on Preference for
Soft Drinks

Mortality - Sample Attrition; Subjects in One Group
some Subjects Withdraw from of a Hair Dying Study
Experiment Marry Rich Widows and
move to Florida

HOW CAN INTERNAL
VALIDITY BE INCREASE?


INCREASING INTERNAL VALIDITY

• Control Group

• Random Assignment

• Pre-testing and Post-testing

• Posttest Only


WHAT ARE THE DIFFERENT
BASIC EXPERIMENTAL
DESIGNS?


Quasi-Experimental Designs

• One Shot Design (After Only)

• One Group Pretest-Posttest

• Static Group Design


ONE SHOT DESIGN (AFTER ONLY)

X O1


One Group Pretest-Posttest

O1 X O2


Static Group Design

Experimental Group X O1
Control Group O2


Three Good Experimental Designs

• Pretest - Posttest Control Group

Design

• Posttest Only Control Group

• Solomon Four Group Design


Pretest-Posttest Control Group Design

Experimental Group R O1 X O2

Control Group R O3 X O4


Posttest Only Control Group

Experimental Group R X O1

Control Group R O2


One-Shot Design
Internal Validity Problems
– weak – not relevant
– weak – weak
– not relevant – weak


One-Group Pretest-Posttest
– weak – weak
– weak – controlled
– weak – controlled


Static-Group Design
– controlled – controlled
– possible source of – weak
concern • Mortality
• Testing – weak
– controlled


Pretest-Posttest Control


Solomon Four-Group Design


Posttest-Only Control


Solomon four Group Design

Experimental Group 1: R O1 X O 2
Control Group 1: R O3 O4
Experimental Group 2: R X O5
Control Group 2: R X O6


ADVANCED EXPERIMENTAL DESIGNS
ARE MORE COMPLEX

• COMPLETELY RANDOMIZED
• RANDOMIZED BLOCK DESIGN
• LATIN SQUARE
• FACTORIAL


Completely randomized design

• An experimental design that uses a
random process to assign subjects (test
units) and treatments to investigate the
effects of only one independent
variable.


Completely Randomized Designs

Control: Experimental Experimental
no music treatment: treatment:
slow music fast music
Average minutes 16 18 12
shopper spends
in store


INDEPENDENT VARIABLE A

Level 1 Level 2 Level 3

Group A Group B Group C


Completely Randomized Design

With a pretest posttest
Group A R O1 X1 O2

Group A R O3 X2 O4

Group A R O5 X3 O6


Completely Randomized Design

With a posttest
Group A R X1 O1

Group B R X2 O2

Group C R X3 O3


Randomized block design

• An extension of the completely randomized
design in which a single extraneous variable
that might affect test units’ response to the
treatment has been identified and the effects
of this variable are isolated by blocking out
its effects.


Randomized Block Design
Independent Variables

Control: Experimental Experimental
no music treatment treatment:
slow music fast music
Blocking variable

Mornings and
afternoons

Evening hours


Factorial design

• An experiment that investigates the
interaction of two or more variables on a
single dependent variable.


Independent Variable 1
No Music Slow Music Fast Music
Independent Variable 2

No Music
cart signs

Grocery
cart signs


Factorial Design -- Roller Skates

Price Red Gold

$25 Cell 1 Cell 4
$30 Cell 2 Cell 5
$35 Cell 3 Cell 6

Package Design


EFFECTS

• Main effect • Interaction effect
• The influence of a • The influence on a
single independent dependent variable by
variable on a combinations of two
dependent variable. or more independent
variables.


2 x 2 Factorial Design

Ad A Ad B

Men 65
> Main Effects
of Gender

Women 65

70 60
>

Main Effects of Ad


Interaction Between Gender and Ad Copy
100

90
Wo
80 me
n
70
Believability

60 Men

50

40

30

20

10
Ad A Ad B

INDEPENDENT VARIABLE 1
Level 1 Level 2

Level 1 Group A Group B
INDEPENDENT
VARIABLE 2

Level 2 Group D
Group C


2 x 2 Factorial with a Pretest Posttest

Group A R O1 X11 O2

Group B R O3 X21 O4

Group C R O5 X12 O6

Group D R O7 X22 O8


2 x 2 Factorial Design with a Posttest
Measure

Group A R X11 O1

Group B R X21 O2

Group C R X12 O3

Group D R X22 O4


A Test Market Experiment on Pricing

Sales in Units (thousands)
Regular Price Reduced Price Cents-Off Coupon
$.99 $.89 Regular Price

Test Market A, B, or C 130 145 153
Test Market D, E, or F 118 143 129
Test Market G, H, or I 87 120 96
Test Market J, K, or L 84 131 99
Mean X1=104.75 X2=134.75 X1=119.25
Grand Mean
X=119.58


LATIN SQUARE DESIGN

• A balanced, two-way classification scheme
that attempts to control or block out the
effect of two or more extraneous factors by
restricting randomization with respect to the
row and column effects.


Order of Usage

SUBJECT 1 2 3

1 A B C
2 B C A
3 C A B


TEST MARKETING

Not just trying But scientific
something testing
out

Controlled experimentation


TEST MARKETING

• AN EXPERIMENTAL PROCEDURE
• THAT PROVIDES AN OPPORTUNITY
TO TEST A NEW PRODUCT OR A NEW
MARKETING PLAN
• UNDER REALISTIC MARKET
CONDITIONS
• TO MEASURE SALES OR
• PROFIT POTENTIAL

FUNCTONS OF
TEST MARKETING

IDENTIFY AND
ESTIMATE CORRECT
OUTCOMES WEAKNESSES
IN PLANS


A Lengthy and Costly Procedure

$$$$$ When not
to Test?

How Long
Loss of Should a
Secrecy Test Last?


SELECTING A TEST MARKET

• POPULATION SIZE
• DEMOGRAPHIC COMPOSITION
• LIFESTYLE CONSIDERATIONS
• COMPETITIVE SITUATION
• MEDIA
• SELF-CONTAINED TRADING AREA
• OVERUSED MARKETS - SECRECY

CONTROL METHOD
OF TEST MARKETING

• SMALL CITY
• LOW CHANCE OF BEING DETECTED
• DISTRIBUTION IS FORCED
(GUARANTEED)


The advantages of using the control
method of test marketing
• Reduced costs
• Shorter time period needed for reading test
market results
• Increased secrecy from competitors
• No distraction of company salespeople from
regular product lines


SOME PROBLEMS ESTIMATING
SALES VOLUME
• OVERATTENTION
• UNREALISTIC STORE CONDITIONS
• READING COMPETIVE
ENVIRONMENT INCORRECTLY
• INCORRECT VOLUME FORECASTS
– ADJUSTED DATA
– PENETRATION AND REPEAT PURCHASE RATE

• TIME LAPSE

High Tech
Test Markets

Electric
Test
Markets
Simulated
Test
Markets Virtual-reality
Simulated
Test Markets


Ch12 2

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