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264a Marketing Research1
Linear Statistical Models
264a Marketing Research2
Answering the questions you have asked.
• Are these ratings really different?
• What is the influence of a policy variable (price, advertising, and etc.) on a market outcome (market shares, sales, overall satisfaction)?
• What is the part worth of a particular feature in a whole bundle that makes a product?
264a Marketing Research3
Are these ratings really different?
• Comparing one mean to a null hypothesis– One Sample t-test
• Comparing two samples means to each other– Two Sample t-test
• What about comparing six mean ratings– Why not 6*5/2 = 15 paired t-tests?
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Degrees of freedom
• We are asking if a series of 6 mean ratings are really all the same (the variations around the mean are just noise).
• We shouldn’t run 15 paired t-tests with only 5 independent pieces of information. A complex pattern of redundancy will make the results deceptive.
264a Marketing Research5
1. How interested would you be in using the following in-vehicle products, information and services?
(1 = not interested at all, 5 = very interested)
Mechanical diagnostics that monitor vehicle vital signs
and report problems to the driver and the dealer 1 2 3 4 5
Information about local services such as hotels, restaurants, copy centers, etc. 1 2 3 4 5
Online shopping 1 2 3 4 5
Emergency roadside assistance if you break down or have an accident 1 2 3 4 5
Entertainment, such as movies, video games, web surfing and music 1 2 3 4 5
Stolen vehicle tracking and recovery 1 2 3 4 5
Send and receive e-mail 1 2 3 4 5
Traffic information updates 1 2 3 4 5
Personal address book and calendar 1 2 3 4 5
Navigation services that provide directions and maps 1 2 3 4 5
Real-time news, weather, sports and business information 1 2 3 4 5
Driving assistance, such as collision avoidance and adaptive cruise control 1 2 3 4 5
Business productivity services such as access to corporate files
or databases, word processing, spreadsheets, etc. 1 2 3 4 5
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Mechanical Diagnostics
0
2040
6080
100
1 2 3 4 5
Info on Local Services
0
20
40
60
1 2 3 4 5
On-Line Shopping
0
50
100
150
1 2 3 4 5
Emergency Roadside Help
0
50
100
150
1 2 3 4 5
Entertainment
0
20
40
60
1 2 3 4 5
Stolen Car Tracking
0
2040
6080
100
1 2 3 4 5
264a Marketing Research7
Interest In Web-Enabled Services
1.0 2.0 3.0 4.0 5.0
a Mechanical Diagnostics
b Info on Local Services
c On-Line Shopping
d Emergency Roadside Help
e Entertainment
f Stolen Car Tracking
g Send and Receive Email
h Traffic info updates
i Personal Address Book and Calendar
j Navigation Services
k Real-Time News etc.
l Collision Avoidance or ACC
m Business Productivity Services
Not at All Interested Very Interested
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264a Marketing Research9
Testing Hypotheses about What Facilities are Most Needed
• Null hypothesis:– The different services are all equally needed
• Alternative hypothesis:– Some kind are rated as more needed than others
• Test statistic– F =Variance Between Groups/Variance Within
– = Signal / Noise
• Decision Rule: Set Alpha at .05
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ANOVASource of Variation SS df MS F P-value F crit
Between Groups 1537.4 12 128.1 106.0 1.1E-210 1.76Within Groups 2860.9 2366 1.2
Total 4398.3 2378
Anova: Single Factor
SUMMARYGroups Count Sum Average Variance
a Mechanical Diagnostics 183 768.4 4.2 1.0b Info on Local Services 183 579 3.2 1.4c On-Line Shopping 183 329 1.8 1.2d Emergency Roadside Help 183 840 4.6 0.5e Entertainment 183 507 2.8 1.7f Stolen Car Tracking 183 770 4.2 1.0g Send and Receive Email 183 618 3.4 1.6h Traffic info updates 183 785 4.3 0.8i Personal Address Book and Calendar 183 568.1 3.1 1.4j Navigation Services 183 782 4.3 0.9k Real-Time News etc. 183 666.6 3.6 1.5l Collision Avoidance or ACC 183 691.6 3.8 1.4m Business Productivity Services 183 440.8 2.4 1.4
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Once you have found a significant difference overall
• Post Hoc Comparisons– You can do as many paired t-tests as you want
without worrying about redundancy.– You can use advanced test (Range Tests) to see
which ratings stand out.
