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Analytics in a Big Data World
Wiley & SAS Business Series
The Wiley & SAS Business Series presents books that help senior‐level
managers with their critical management decisions.
Titles in the Wiley & SAS Business Series include:
Activity‐Based Management for Financial Institutions: Driving Bottom‐
Line Results by Brent Bahnub
Bank Fraud: Using Technology to Combat Losses by Revathi Subramanian
Big Data Analytics: Turning Big Data into Big Money by Frank Ohlhorst
Branded! How Retailers Engage Consumers with Social Media and Mobil-
ity by Bernie Brennan and Lori Schafer
Business Analytics for Customer Intelligence by Gert Laursen
Business Analytics for Managers: Taking Business Intelligence beyond
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The Business Forecasting Deal: Exposing Bad Practices and Providing
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Business Intelligence Applied: Implementing an Effective Information and
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Business Intelligence in the Cloud: Strategic Implementation Guide by
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Business Intelligence Success Factors: Tools for Aligning Your Business in
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CIO Best Practices: Enabling Strategic Value with Information Technology,
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Connecting Organizational Silos: Taking Knowledge Flow Management to
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Credit Risk Assessment: The New Lending System for Borrowers, Lenders,
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Credit Risk Scorecards: Developing and Implementing Intelligent Credit
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The Data Asset: How Smart Companies Govern Their Data for Business
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Delivering Business Analytics: Practical Guidelines for Best Practice by
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Demand‐Driven Forecasting: A Structured Approach to Forecasting, Sec-
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Demand‐Driven Inventory Optimization and Replenishment: Creating a
More Effi cient Supply Chain by Robert A. Davis
The Executive’s Guide to Enterprise Social Media Strategy: How Social Net-
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Mike Barlow
Economic and Business Forecasting: Analyzing and Interpreting Econo-
metric Results by John Silvia, Azhar Iqbal, Kaylyn Swankoski, Sarah
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Executive’s Guide to Solvency II by David Buckham, Jason Wahl, andI
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Fair Lending Compliance: Intelligence and Implications for Credit Risk
Management by Clark R. Abrahams and Mingyuan Zhangt
Foreign Currency Financial Reporting from Euros to Yen to Yuan: A Guide
to Fundamental Concepts and Practical Applications by Robert Rowan
Health Analytics: Gaining the Insights to Transform Health Care by Jason
Burke
Heuristics in Analytics: A Practical Perspective of What Infl uences Our
Analytical World by Carlos Andre Reis Pinheiro and Fiona McNeilld
Human Capital Analytics: How to Harness the Potential of Your Organiza-
tion’s Greatest Asset by Gene Pease, Boyce Byerly, and Jac Fitz‐enz t
Implement, Improve and Expand Your Statewide Longitudinal Data Sys-
tem: Creating a Culture of Data in Education by Jamie McQuiggan and
Armistead Sapp
Information Revolution: Using the Information Evolution Model to Grow
Your Business by Jim Davis, Gloria J. Miller, and Allan Russell
Killer Analytics: Top 20 Metrics Missing from Your Balance Sheet by Markt
Brown
Manufacturing Best Practices: Optimizing Productivity and Product Qual-
ity by Bobby Hull
Marketing Automation: Practical Steps to More Effective Direct Marketing
by Jeff LeSueur
Mastering Organizational Knowledge Flow: How to Make Knowledge
Sharing Work by Frank Leistnerk
The New Know: Innovation Powered by Analytics by Thornton May
Performance Management: Integrating Strategy Execution, Methodologies,
Risk, and Analytics by Gary Cokins
Predictive Business Analytics: Forward‐Looking Capabilities to Improve
Business Performance by Lawrence Maisel and Gary Cokins
Retail Analytics: The Secret Weapon by Emmett Cox
Social Network Analysis in Telecommunications by Carlos Andre Reis
Pinheiro
Statistical Thinking: Improving Business Performance, second edition by
Roger W. Hoerl and Ronald D. Snee
Taming the Big Data Tidal Wave: Finding Opportunities in Huge Data
Streams with Advanced Analytics by Bill Franks
Too Big to Ignore: The Business Case for Big Data by Phil Simon
The Value of Business Analytics: Identifying the Path to Profi tability by
Evan Stubbs
Visual Six Sigma: Making Data Analysis Lean by Ian Cox, Marie A.
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Win with Advanced Business Analytics: Creating Business Value from
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Analytics in a Big Data World
The Essential Guide to Data Science and Its Applications
Bart Baesens
Cover image: ©iStockphoto/vlastosCover design: Wiley
Copyright © 2014 by Bart Baesens. All rights reserved.
Published by John Wiley & Sons, Inc., Hoboken, New Jersey.Published simultaneously in Canada.
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Library of Congress Cataloging-in-Publication Data:Baesens, Bart. Analytics in a big data world : the essential guide to data science and its applications / Bart Baesens. 1 online resource. — (Wiley & SAS business series) Description based on print version record and CIP data provided by publisher; resource not viewed. ISBN 978-1-118-89271-8 (ebk); ISBN 978-1-118-89274-9 (ebk);ISBN 978-1-118-89270-1 (cloth) 1. Big data. 2. Management—Statistical methods. 3. Management—Data processing. 4. Decision making—Data processing. I. Title. HD30.215658.4’038 dc23 2014004728
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
To my wonderful wife, Katrien, and my kids,Ann-Sophie, Victor, and Hannelore. To my parents and parents-in-law.
ix
Contents
Preface xiii
Acknowledgments xv
Chapter 1 Big Data and Analytics 1
Example Applications 2
Basic Nomenclature 4
Analytics Process Model 4
Job Profi les Involved 6
Analytics 7
Analytical Model Requirements 9
Notes 10
Chapter 2 Data Collection, Sampling,
and Preprocessing 13
Types of Data Sources 13
Sampling 15
Types of Data Elements 17
Visual Data Exploration and Exploratory
Statistical Analysis 17
Missing Values 19
Outlier Detection and Treatment 20
Standardizing Data 24
Categorization 24
Weights of Evidence Coding 28
Variable Selection 29
x ▸ CONTENTS
Segmentation 32
Notes 33
Chapter 3 Predictive Analytics 35
Target Defi nition 35
Linear Regression 38
Logistic Regression 39
Decision Trees 42
Neural Networks 48
Support Vector Machines 58
Ensemble Methods 64
Multiclass Classifi cation Techniques 67
Evaluating Predictive Models 71
Notes 84
Chapter 4 Descriptive Analytics 87
Association Rules 87
Sequence Rules 94
Segmentation 95
Notes 104
Chapter 5 Survival Analysis 105
Survival Analysis Measurements 106
Kaplan Meier Analysis 109
Parametric Survival Analysis 111
Proportional Hazards Regression 114
Extensions of Survival Analysis Models 116
Evaluating Survival Analysis Models 117
Notes 117
Chapter 6 Social Network Analytics 119
Social Network Defi nitions 119
Social Network Metrics 121
Social Network Learning 123
Relational Neighbor Classifi er 124
C O N T E N T S ◂ xi
Probabilistic Relational Neighbor Classifi er 125
Relational Logistic Regression 126
Collective Inferencing 128
Egonets 129
Bigraphs 130
Notes 132
Chapter 7 Analytics: Putting It All to Work 133
Backtesting Analytical Models 134
Benchmarking 146
Data Quality 149
Software 153
Privacy 155
Model Design and Documentation 158
Corporate Governance 159
Notes 159
Chapter 8 Example Applications 161
Credit Risk Modeling 161
Fraud Detection 165
Net Lift Response Modeling 168
Churn Prediction 172
Recommender Systems 176
Web Analytics 185
Social Media Analytics 195
Business Process Analytics 204
Notes 220
About the Author 223
Index 225
xiii
Preface
Companies are being fl ooded with tsunamis of data collected in a
multichannel business environment, leaving an untapped poten-
tial for analytics to better understand, manage, and strategically
exploit the complex dynamics of customer behavior. In this book, we
will discuss how analytics can be used to create strategic leverage and
identify new business opportunities.
The focus of this book is not on the mathematics or theory, but on
the practical application. Formulas and equations will only be included
when absolutely needed from a practitioner’s perspective. It is also not
our aim to provide exhaustive coverage of all analytical techniques
previously developed, but rather to cover the ones that really provide
added value in a business setting.
The book is written in a condensed, focused way because it is tar-
geted at the business professional. A reader’s prerequisite knowledge
should consist of some basic exposure to descriptive statistics (e.g.,
mean, standard deviation, correlation, confi dence intervals, hypothesis
testing), data handling (using, for example, Microsoft Excel, SQL, etc.),
and data visualization (e.g., bar plots, pie charts, histograms, scatter
plots). Throughout the book, many examples of real‐life case studies
will be included in areas such as risk management, fraud detection,
customer relationship management, web analytics, and so forth. The
author will also integrate both his research and consulting experience
throughout the various chapters. The book is aimed at senior data ana-
lysts, consultants, analytics practitioners, and PhD researchers starting
to explore the fi eld.
Chapter 1 discusses big data and analytics. It starts with some
example application areas, followed by an overview of the analytics
process model and job profi les involved, and concludes by discussing
key analytic model requirements. Chapter 2 provides an overview of
xiv ▸ PREFACE
data collection, sampling, and preprocessing. Data is the key ingredi-
ent to any analytical exercise, hence the importance of this chapter.
It discusses sampling, types of data elements, visual data exploration
and exploratory statistical analysis, missing values, outlier detection
and treatment, standardizing data, categorization, weights of evidence
coding, variable selection, and segmentation. Chapter 3 discusses pre-
dictive analytics. It starts with an overview of the target defi nition
and then continues to discuss various analytics techniques such as
linear regression, logistic regression, decision trees, neural networks,
support vector machines, and ensemble methods (bagging, boost-
ing, random forests). In addition, multiclass classifi cation techniques
are covered, such as multiclass logistic regression, multiclass deci-
sion trees, multiclass neural networks, and multiclass support vector
machines. The chapter concludes by discussing the evaluation of pre-
dictive models. Chapter 4 covers descriptive analytics. First, association
rules are discussed that aim at discovering intratransaction patterns.
This is followed by a section on sequence rules that aim at discovering
intertransaction patterns. Segmentation techniques are also covered.
Chapter 5 introduces survival analysis. The chapter starts by introduc-
ing some key survival analysis measurements. This is followed by a
discussion of Kaplan Meier analysis, parametric survival analysis, and
proportional hazards regression. The chapter concludes by discussing
various extensions and evaluation of survival analysis models. Chap-
ter 6 covers social network analytics. The chapter starts by discussing
example social network applications. Next, social network defi nitions
and metrics are given. This is followed by a discussion on social network
learning. The relational neighbor classifi er and its probabilistic variant
together with relational logistic regression are covered next. The chap-
ter ends by discussing egonets and bigraphs. Chapter 7 provides an
overview of key activities to be considered when putting analytics to
work. It starts with a recapitulation of the analytic model requirements
and then continues with a discussion of backtesting, benchmarking,
data quality, software, privacy, model design and documentation, and
corporate governance. Chapter 8 concludes the book by discussing var-
ious example applications such as credit risk modeling, fraud detection,
net lift response modeling, churn prediction, recommender systems,
web analytics, social media analytics, and business process analytics.
xv
Acknowledgments
I would like to acknowledge all my colleagues who contributed to
this text: Seppe vanden Broucke, Alex Seret, Thomas Verbraken,
Aimée Backiel, Véronique Van Vlasselaer, Helen Moges, and Barbara
Dergent.
Analytics in a Big Data World
1
C H A P T E R 1 Big Data and Analytics
Data are everywhere. IBM projects that every day we generate 2.5
quintillion bytes of data.1 In relative terms, this means 90 percent
of the data in the world has been created in the last two years.
Gartner projects that by 2015, 85 percent of Fortune 500 organizations
will be unable to exploit big data for competitive advantage and about
4.4 million jobs will be created around big data. 2 Although these esti-
mates should not be interpreted in an absolute sense, they are a strong
indication of the ubiquity of big data and the strong need for analytical
skills and resources because, as the data piles up, managing and analyz-
ing these data resources in the most optimal way become critical suc-
cess factors in creating competitive advantage and strategic leverage.
Figure 1.1 shows the results of a KDnuggets 3 poll conducted dur-
ing April 2013 about the largest data sets analyzed. The total number
of respondents was 322 and the numbers per category are indicated
between brackets. The median was estimated to be in the 40 to 50 giga-
byte (GB) range, which was about double the median answer for a simi-
lar poll run in 2012 (20 to 40 GB). This clearly shows the quick increase
in size of data that analysts are working on. A further regional break-
down of the poll showed that U.S. data miners lead other regions in big
data, with about 28% of them working with terabyte (TB) size databases.
A main obstacle to fully harnessing the power of big data using ana-
lytics is the lack of skilled resources and “data scientist” talent required to
2 ▸ ANALYTICS IN A B IG DATA WORLD
exploit big data. In another poll ran by KDnuggets in July 2013, a strong
need emerged for analytics/big data/data mining/data science educa-
tion.4 It is the purpose of this book to try and fi ll this gap by providing a
concise and focused overview of analytics for the business practitioner.
EXAMPLE APPLICATIONS
Analytics is everywhere and strongly embedded into our daily lives. As I
am writing this part, I was the subject of various analytical models today.
When I checked my physical mailbox this morning, I found a catalogue
sent to me most probably as a result of a response modeling analytical
exercise that indicated that, given my characteristics and previous pur-
chase behavior, I am likely to buy one or more products from it. Today,
I was the subject of a behavioral scoring model of my fi nancial institu-
tion. This is a model that will look at, among other things, my check-
ing account balance from the past 12 months and my credit payments
during that period, together with other kinds of information available
to my bank, to predict whether I will default on my loan during the
next year. My bank needs to know this for provisioning purposes. Also
today, my telephone services provider analyzed my calling behavior
Figure 1.1 Results from a KDnuggets Poll about Largest Data Sets Analyzed Source: www.kdnuggets.com/polls/2013/largest‐dataset‐analyzed‐data‐mined‐2013.html.
Less than 1 MB (12) 3.7%
1.1 to 10 MB (8) 2.5%
11 to 100 MB (14) 4.3%
101 MB to 1 GB (50) 15.5%
1.1 to 10 GB (59)18%
11 to 100 GB (52) 16%
101 GB to 1 TB(59) 18%
1.1 to 10 TB (39) 12%
11 to 100 TB (15) 4.7%
101 TB to 1 PB (6) 1.9%
1.1 to 10 PB (2) 0.6%
11 to 100 PB (0) 0%
Over 100 PB (6) 1.9%
B I G D A T A A N D A N A L Y T I C S ◂ 3
and my account information to predict whether I will churn during the
next three months. As I logged on to my Facebook page, the social ads
appearing there were based on analyzing all information (posts, pictures,
my friends and their behavior, etc.) available to Facebook. My Twitter
posts will be analyzed (possibly in real time) by social media analytics to
understand both the subject of my tweets and the sentiment of them.
As I checked out in the supermarket, my loyalty card was scanned fi rst,
followed by all my purchases. This will be used by my supermarket to
analyze my market basket, which will help it decide on product bun-
dling, next best offer, improving shelf organization, and so forth. As I
made the payment with my credit card, my credit card provider used
a fraud detection model to see whether it was a legitimate transaction.
When I receive my credit card statement later, it will be accompanied by
various vouchers that are the result of an analytical customer segmenta-
tion exercise to better understand my expense behavior.
To summarize, the relevance, importance, and impact of analytics
are now bigger than ever before and, given that more and more data
are being collected and that there is strategic value in knowing what
is hidden in data, analytics will continue to grow. Without claiming to
be exhaustive, Table 1.1 presents some examples of how analytics is
applied in various settings.
Table 1.1 Example Analytics Applications
Marketing
Risk
Management Government Web Logistics Other
Response
modeling
Credit risk
modeling
Tax avoidance Web analytics Demand
forecasting
Text
analytics
Net lift
modeling
Market risk
modeling
Social
security fraud
Social media
analytics
Supply chain
analytics
Business
process
analytics
Retention
modeling
Operational
risk modeling
Money
laundering
Multivariate
testing
Market basket
analysis
Fraud
detection
Terrorism
detection
Recommender
systems
Customer
segmentation
4 ▸ ANALYTICS IN A B IG DATA WORLD
It is the purpose of this book to discuss the underlying techniques
and key challenges to work out the applications shown in Table 1.1
using analytics. Some of these applications will be discussed in further
detail in Chapter 8 .
BASIC NOMENCLATURE
In order to start doing analytics, some basic vocabulary needs to be
defi ned. A fi rst important concept here concerns the basic unit of anal-
ysis. Customers can be considered from various perspectives. Customer
lifetime value (CLV) can be measured for either individual customers
or at the household level. Another alternative is to look at account
behavior. For example, consider a credit scoring exercise for which
the aim is to predict whether the applicant will default on a particular
mortgage loan account. The analysis can also be done at the transac-
tion level. For example, in insurance fraud detection, one usually per-
forms the analysis at insurance claim level. Also, in web analytics, the
basic unit of analysis is usually a web visit or session.
It is also important to note that customers can play different roles.
For example, parents can buy goods for their kids, such that there is
a clear distinction between the payer and the end user. In a banking
setting, a customer can be primary account owner, secondary account
owner, main debtor of the credit, codebtor, guarantor, and so on. It
is very important to clearly distinguish between those different roles
when defi ning and/or aggregating data for the analytics exercise.
Finally, in case of predictive analytics, the target variable needs to
be appropriately defi ned. For example, when is a customer considered
to be a churner or not, a fraudster or not, a responder or not, or how
should the CLV be appropriately defi ned?
ANALYTICS PROCESS MODEL
Figure 1.2 gives a high‐level overview of the analytics process model. 5
As a fi rst step, a thorough defi nition of the business problem to be
solved with analytics is needed. Next, all source data need to be identi-
fi ed that could be of potential interest. This is a very important step, as
data is the key ingredient to any analytical exercise and the selection of
B I G D A T A A N D A N A L Y T I C S ◂ 5
data will have a deterministic impact on the analytical models that will
be built in a subsequent step. All data will then be gathered in a stag-
ing area, which could be, for example, a data mart or data warehouse.
Some basic exploratory analysis can be considered here using, for
example, online analytical processing (OLAP) facilities for multidimen-
sional data analysis (e.g., roll‐up, drill down, slicing and dicing). This
will be followed by a data cleaning step to get rid of all inconsistencies,
such as missing values, outliers, and duplicate data. Additional trans-
formations may also be considered, such as binning, alphanumeric to
numeric coding, geographical aggregation, and so forth. In the analyt-
ics step, an analytical model will be estimated on the preprocessed and
transformed data. Different types of analytics can be considered here
(e.g., to do churn prediction, fraud detection, customer segmentation,
market basket analysis). Finally, once the model has been built, it will
be interpreted and evaluated by the business experts. Usually, many
trivial patterns will be detected by the model. For example, in a market
basket analysis setting, one may fi nd that spaghetti and spaghetti sauce
are often purchased together. These patterns are interesting because
they provide some validation of the model. But of course, the key issue
here is to fi nd the unexpected yet interesting and actionable patterns
(sometimes also referred to as knowledge diamonds ) that can provide
added value in the business setting. Once the analytical model has
been appropriately validated and approved, it can be put into produc-
tion as an analytics application (e.g., decision support system, scoring
engine). It is important to consider here how to represent the model
output in a user‐friendly way, how to integrate it with other applica-
tions (e.g., campaign management tools, risk engines), and how to
make sure the analytical model can be appropriately monitored and
backtested on an ongoing basis.
It is important to note that the process model outlined in Fig-
ure 1.2 is iterative in nature, in the sense that one may have to go back
to previous steps during the exercise. For example, during the analyt-
ics step, the need for additional data may be identifi ed, which may
necessitate additional cleaning, transformation, and so forth. Also, the
most time consuming step is the data selection and preprocessing step;
this usually takes around 80% of the total efforts needed to build an
analytical model.
6 ▸ ANALYTICS IN A B IG DATA WORLD
JOB PROFILES INVOLVED
Analytics is essentially a multidisciplinary exercise in which many
different job profi les need to collaborate together. In what follows, we
will discuss the most important job profi les.
The database or data warehouse administrator (DBA) is aware of
all the data available within the fi rm, the storage details, and the data
defi nitions. Hence, the DBA plays a crucial role in feeding the analyti-
cal modeling exercise with its key ingredient, which is data. Because
analytics is an iterative exercise, the DBA may continue to play an
important role as the modeling exercise proceeds.
Another very important profi le is the business expert. This could,
for example, be a credit portfolio manager, fraud detection expert,
brand manager, or e‐commerce manager. This person has extensive
business experience and business common sense, which is very valu-
able. It is precisely this knowledge that will help to steer the analytical
modeling exercise and interpret its key fi ndings. A key challenge here
is that much of the expert knowledge is tacit and may be hard to elicit
at the start of the modeling exercise.
Legal experts are becoming more and more important given that
not all data can be used in an analytical model because of privacy,
Figure 1.2 The Analytics Process Model
Understandingwhat data isneeded for theapplication
Data Cleaning
Interpretation and Evaluation
DataTransformation(binning, alpha tonumeric, etc.)
Analytics
DataSelection
SourceData
AnalyticsApplication
PreprocessedData
TransformedData
Patterns
Data MiningMart
Dumps of Operational Data
B I G D A T A A N D A N A L Y T I C S ◂ 7
discrimination, and so forth. For example, in credit risk modeling, one
can typically not discriminate good and bad customers based upon
gender, national origin, or religion. In web analytics, information is
typically gathered by means of cookies, which are fi les that are stored
on the user’s browsing computer. However, when gathering informa-
tion using cookies, users should be appropriately informed. This is sub-
ject to regulation at various levels (both national and, for example,
European). A key challenge here is that privacy and other regulation
highly vary depending on the geographical region. Hence, the legal
expert should have good knowledge about what data can be used
when, and what regulation applies in what location.
The data scientist, data miner, or data analyst is the person respon-
sible for doing the actual analytics. This person should possess a thor-
ough understanding of all techniques involved and know how to
implement them using the appropriate software. A good data scientist
should also have good communication and presentation skills to report
the analytical fi ndings back to the other parties involved.
The software tool vendors should also be mentioned as an
important part of the analytics team. Different types of tool vendors can
be distinguished here. Some vendors only provide tools to automate
specifi c steps of the analytical modeling process (e.g., data preprocess-
ing). Others sell software that covers the entire analytical modeling
process. Some vendors also provide analytics‐based solutions for spe-
cifi c application areas, such as risk management, marketing analytics
and campaign management, and so on.
ANALYTICS
Analytics is a term that is often used interchangeably with data science,
data mining, knowledge discovery, and others. The distinction between
all those is not clear cut. All of these terms essentially refer to extract-
ing useful business patterns or mathematical decision models from a
preprocessed data set. Different underlying techniques can be used for
this purpose, stemming from a variety of different disciplines, such as:
■ Statistics (e.g., linear and logistic regression)
■ Machine learning (e.g., decision trees)
8 ▸ ANALYTICS IN A B IG DATA WORLD
■ Biology (e.g., neural networks, genetic algorithms, swarm intel-
ligence)
■ Kernel methods (e.g., support vector machines)
Basically, a distinction can be made between predictive and descrip-
tive analytics. In predictive analytics, a target variable is typically avail-
able, which can either be categorical (e.g., churn or not, fraud or not)
or continuous (e.g., customer lifetime value, loss given default). In
descriptive analytics, no such target variable is available. Common
examples here are association rules, sequence rules, and clustering.
Figure 1.3 provides an example of a decision tree in a classifi cation
predictive analytics setting for predicting churn.
More than ever before, analytical models steer the strategic risk
decisions of companies. For example, in a bank setting, the mini-
mum equity and provisions a fi nancial institution holds are directly
determined by, among other things, credit risk analytics, market risk
analytics, operational risk analytics, fraud analytics, and insurance
risk analytics. In this setting, analytical model errors directly affect
profi tability, solvency, shareholder value, the macroeconomy, and
society as a whole. Hence, it is of the utmost importance that analytical
Figure 1.3 Example of Classifi cation Predictive Analytics
Customer Age Recency Frequency Monetary Churn
John 35 5 6 100 Yes
Sophie 18 10 2 150 No
Victor 38 28 8 20 No
Laura 44 12 4 280 Yes
AnalyticsSoftware
Age < 40
Yes
Yes
Churn No Churn Churn No Churn
Yes
No
No No
Recency < 10 Frequency < 5
B I G D A T A A N D A N A L Y T I C S ◂ 9
models are developed in the most optimal way, taking into account
various requirements that will be discussed in what follows.
ANALYTICAL MODEL REQUIREMENTS
A good analytical model should satisfy several requirements, depend-
ing on the application area. A fi rst critical success factor is business
relevance. The analytical model should actually solve the business
problem for which it was developed. It makes no sense to have a work-
ing analytical model that got sidetracked from the original problem
statement. In order to achieve business relevance, it is of key impor-
tance that the business problem to be solved is appropriately defi ned,
qualifi ed, and agreed upon by all parties involved at the outset of the
analysis.
A second criterion is statistical performance. The model should
have statistical signifi cance and predictive power. How this can be mea-
sured will depend upon the type of analytics considered. For example,
in a classifi cation setting (churn, fraud), the model should have good
discrimination power. In a clustering setting, the clusters should be as
homogenous as possible. In later chapters, we will extensively discuss
various measures to quantify this.
Depending on the application, analytical models should also be
interpretable and justifi able. Interpretability refers to understanding
the patterns that the analytical model captures. This aspect has a
certain degree of subjectivism, since interpretability may depend on
the business user’s knowledge. In many settings, however, it is con-
sidered to be a key requirement. For example, in credit risk modeling
or medical diagnosis, interpretable models are absolutely needed to
get good insight into the underlying data patterns. In other settings,
such as response modeling and fraud detection, having interpretable
models may be less of an issue. Justifi ability refers to the degree to
which a model corresponds to prior business knowledge and intu-
ition. 6 For example, a model stating that a higher debt ratio results
in more creditworthy clients may be interpretable, but is not justifi -
able because it contradicts basic fi nancial intuition. Note that both
interpretability and justifi ability often need to be balanced against
statistical performance. Often one will observe that high performing
10 ▸ ANALYTICS IN A B IG DATA WORLD
analytical models are incomprehensible and black box in nature.
A popular example of this is neural networks, which are universal
approximators and are high performing, but offer no insight into the
underlying patterns in the data. On the contrary, linear regression
models are very transparent and comprehensible, but offer only
limited modeling power.
Analytical models should also be operationally effi cient. This refers tot
the efforts needed to collect the data, preprocess it, evaluate the model,
and feed its outputs to the business application (e.g., campaign man-
agement, capital calculation). Especially in a real‐time online scoring
environment (e.g., fraud detection) this may be a crucial characteristic.
Operational effi ciency also entails the efforts needed to monitor and
backtest the model, and reestimate it when necessary.
Another key attention point is the economic cost needed to set upt
the analytical model. This includes the costs to gather and preprocess
the data, the costs to analyze the data, and the costs to put the result-
ing analytical models into production. In addition, the software costs
and human and computing resources should be taken into account
here. It is important to do a thorough cost–benefi t analysis at the start
of the project.
Finally, analytical models should also comply with both local and
international regulation and legislation . For example, in a credit risk set-
ting, the Basel II and Basel III Capital Accords have been introduced
to appropriately identify the types of data that can or cannot be used
to build credit risk models. In an insurance setting, the Solvency II
Accord plays a similar role. Given the importance of analytics nowa-
days, more and more regulation is being introduced relating to the
development and use of the analytical models. In addition, in the con-
text of privacy, many new regulatory developments are taking place at
various levels. A popular example here concerns the use of cookies in
a web analytics context.
NOTES
1. IBM, www.ibm.com/big‐data/us/en , 2013.
2. www.gartner.com/technology/topics/big‐data.jsp .
3. www.kdnuggets.com/polls/2013/largest‐dataset‐analyzed‐data‐mined‐2013.html .
4. www.kdnuggets.com/polls/2013/analytics‐data‐science‐education.html .
B I G D A T A A N D A N A L Y T I C S ◂ 11
5. J. Han and M. Kamber, Data Mining: Concepts and Techniques, 2nd ed. (MorganKaufmann, Waltham, MA, US, 2006); D. J. Hand, H. Mannila, and P. Smyth, Prin-ciples of Data Mining (MIT Press, Cambridge , Massachusetts, London, England, 2001); P. N. Tan, M. Steinbach, and V. Kumar, Introduction to Data Mining (Pearson, UpperSaddle River, New Jersey, US, 2006).
6. D. Martens, J. Vanthienen, W. Verbeke, and B. Baesens, “Performance of Classifi ca-tion Models from a User Perspective.” Special issue, Decision Support Systems 51, no. 4 (2011): 782–793.