Data Warehousing and Data Mining

Winter Semester 2010/2011Free University of Bozen, Bolzano

DW Lecturer:

Johann Gampergamper@inf.unibz.it

DM Lecturer:

Mouna Kacimimouna.kacimi@unibz.it

http://www.inf.unibz.it/dis/teaching/DWDM/index.html

OrganizationLecturesTuesday & Friday From 10:30 To 12:30 Office hours Dr. Kacimi: Tuesday From 14:00 to 16:00

(appointment by email) ProjectsLab hours Friday From 14:00 to 16:00

Announcements• There will be no class on Friday, October 8• Lab hours might change to be from 15:00 to 17:00

Textbooks• Jiawei Han and Micheline Kamber, “Data Mining: Concepts and

Techniques”, Second Edition, 2006• Pang-Ning Tan, Michael Steinbach, and Vipin Kumar, "Introduction to

Data Mining", Pearson Addison Wesley, 2008, ISBN: 0-32-134136-7• Margaret H. Dunham, “Data Mining: Introductory and Advanced

Topics”, Prentice Hall, 2003

Exam ProcedureRequirements: obtain 18 credit points in each of the following

ProjectExam

Final grade= Project_grade× 0.6+ Exam_grade × 0.4Important

A successful project remains validIf a project is unsuccessful until the day of the Exam, its validity expires

More about Project and Exam

Project: - work in groups- data analysis/apply DM methods on real datasets/

implement DM algorithms - write a project report and present the project

Exam: - have knowledge about the course- be able to present it

Data Mining

Outline

Introduction to Data Mining

Data Analysis and Uncertainty

Classification & Prediction

Cluster Analysis

Applications

Part I: Introduction & Foundations

Part II: Supervised Learning

Part III: Unsupervised Learning

Part IV: Summary & Open problems

Chapter I: Introduction & Foundations

1.1 Introduction 1.1.1 Definitions & Motivations 1.1.2 Data to be Mined1.1.3 Knowledge to be discovered 1.1.4 Techniques Utilized 1.1.5 Applications Adapted1.1.6 Major Issues in Data Mining

1.2 Getting to Know Your Data1.2.1 Data Objects and Attribute Types1.2.2 Basic Statistical Descriptions of Data1.2.3 Measuring Data Similarity and Dissimilarity

1.3 Basics from Probability Theory and Statistics 13.1 Probability Theory1.3.2 Statistical Inference: Sampling and Estimation 1.3.3 Statistical Inference: Hypothesis Testing and Regression

1.1 Definitions & Motivations

Explosive Growth of Data: from terabytes to petabytesData Collections and Data Availability

Crawlers, database systems, Web, etc.

Sources

Business: Web, e-commerce, transactions, etc.

Science: Remote sensing, bioinformatics, etc.

Society and everyone: news, YouTube, etc.

Problem: We are drowning in data, but starving for knowledge!

Solution: Use Data Mining tools for Automated Analysis of massive data sets

Why Data Mining?

What is Data Mining?

Data mining (knowledge discovery from data) Extraction of interesting (non-trivial, implicit, previously unknownand potentially useful) patterns or knowledge from huge amount of dataData mining: a misnomer?

Alternative namesKnowledge discovery (mining) in databases (KDD), knowledge extraction, data/pattern analysis, data archeology, data dredging, information harvesting, business intelligence, etc.

Gold Mining Not Stone Mining

Knowledge Knowledge Mining?

Stone

Data

Knowledge Discovery (KDD) Process

Data Mining as a step in the knowledge discovery process

Data Cleaning

& Integration

Databases

Data Mining

Data Warehouse

Task-relevantData

Selection& transformation

Data mining plays an essential role in the knowledge discovery process

Evaluation & Presentation

Knowledge

Patterns

Knowledge Discovery (KDD) ProcessData Cleaning

Remove noise and inconsistent dataData Integration

Combine multiple data sources Data Selection

Data relevant to analysis tasks are retrieved form the data

Data transformationTransform data into appropriate form for mining (summary, aggregation, etc.)

Data mining Extract data patterns

Pattern EvaluationIdentify truly interesting patterns

Knowledge representation Use visualization and knowledge representation tools to present the mined data to the user

Data

Cleaning

& Integration

Databases

Data Mining

Data Warehouse

Task-relevant

Data

Selection

& transformation

Evaluation

& Presentation

Knowledge

Patterns

Typical Architecture of a Data Mining System

DatabaseData

WarehouseWorld Wide

WebOther InfoRepositories

Database or Data Warehouse Server

Data Mining Engine

Pattern Evaluation

User Interface

Knowledge Base

Data cleaning, Integration and selection

Knowledge BaseGuide the searchEvaluate interestingness of the results

IncludeConcept hierarchies User believesConstraints, thresholds, metadata, etc.

Confluence of Multiple Disciplines

Data Mining

Database Technology Statistics

MachineLearning

PatternRecognition

AlgorithmOther

Disciplines

Visualization

Why Confluence of Multiple Disciplines?

Tremendous amount of dataScalable algorithms to handle terabytes of data (e.g., Flickr had 5 billion images in September, 2010 [http://blog.flickr.net/en/2010/09/19/5000000000/])

High dimensionality of dataData can have tens of thousands of features (e,g., DNA microarray)

High complexity of dataData can be highly complex, can be of different types, and can include different descriptors

Images can be described using text and visual features such ascolor, texture, contours, etc. Videos can be described using text, images and their descriptors, audio phonemes, etc.Social networks can have a complex structure...

New and sophisticated applicationsApplications can be difficult (e.g., medical applications).

Different Views of Data Mining

Data View

Kinds of data to be mined

Knowledge view

Kinds of knowledge to be discovered

Method view

Kinds of techniques utilized

Application view

Kinds of applications

1.1.2 Data to be Mined

In principle, data mining should be applicable to any data repository

This lecture includes examples about:

Relational databasesData warehousesTransactional databasesAdvanced database systems

Relational Databases

Database System Collection of interrelated data, known as databaseA set of software programs that manage and access the data

Relational Databases (RD)A collection of tables. Each one has a unique nameA table contains a set of attributes (columns) & tuples (rows). Each object in a relational table has a unique key and is described by a set of attribute values. Data are accessed using database

queries (SQL): projection, join, etc.Data Mining applied to RD

Search for trends or data patternsExample:

predict the credit risk of costumers based on their income, age and expenses.

cust_Id Name age income152...

Anna...

27...

24000 €...

trans_Id cust_Id method AmountT156...

152...

Visa...

1357 €...

Costumers

Purchases

Data Warehouses

A data warehouse (DW) is a repository of information collected from multiple sources, stored under a unified schema.

Data organized around major subjects (using summarization)Multidimensional database structure (e.g., data Cube)

Dimension = one attribute or a set of attributesCell = stores the value of some aggregated measures.

Data Mining applied to DWData warehouse tools help data analysisData Mining tools are required to allow more in-depth and automated analysis

Data sourcein Bolzano

Data sourcein Paris

Data sourcein Madrid

Data Warehouse

CleanIntegrateTransformLoadrefresh

Query and Analysis Tools

Client

Client

Transactional Databases

A transactional database (TD) consists of a file where each record represents a transaction. A transaction includes a unique transaction identifier (trans_id) and a list of the items making the transaction. A transaction database may include other tables containing other information regarding the sale(customer_Id, location, etc.)Basic analysis (examples)

Show me all the items purchased by David Winston?How many transactions include item number 5?

Data Mining on TDPerform a deeper analysisExample: Which items sold well together?Basically, data mining systems can identify frequent sets in transactional databases and perform market basket data analysis.

trans_Id List of items_IDs

T100 I1,I3,I8,I16

T200 I2,I8

... ...

Advanced Database Systems(1)

Advanced database systems provide tools for handling complex data

Spatial data (e.g., maps)Engineering design data (e.g., buildings, system components)Hypertext and multimedia data (text, image, audio, and video)Time-related data (e.g., historical records)Stream data (e.g., video surveillance and sensor data)World Wide Web, a huge, widely distributed information repository made available by Internet

Require efficient data structures and scalable methods to handleComplex object structures and variable length recordsSemi structured or unstructured dataMultimedia and spatiotemporal data Database schema with complex and dynamic structures

Advanced Database Systems(2) Example: World Wide Web

Provide rich, worldwide, online and distributed information services.Data objects are linked togetherUsers traverse from one object via links to anotherProblems

Data can be highly unstructuredDifficult to understand the semantic of web pages and their context.

Data Mining on WWWWeb usage Mining (user access pattern)

Improve system design (efficiency)Better marketing decisions (adverts, user profile)

Authoritative Web page Analysis Ranking web pages based on their importance

Automated Web page clustering and classificationGroup and arrange web pages based on their content

Web community analysisIdentify hidden web social networks and observe their evolution

1.1.3 Knowledge to be Discovered

Data mining functionalities are used to specify the kind of patterns to be found in data mining tasksData mining tasks can be classified into two categories

Descriptive : Characterize the general properties of the dataPredictive : Perform inference on the current data to make

predictions What to extract?

Users may not have an idea about what kinds of patterns in theirdata can be interesting

What to do?Have a data mining system that can mine multiple types of patterns to handle different user and application needs. Discover patterns at various granularities (levels of abstraction)Allow users to guide the search for interesting patterns

CountryCityStreet Example of differentgranularities

Characterization and Discrimination (1)

Data can be associated with classes or concepts

Class/Concept descriptions: describe individual classes and concepts in summarized, concise, and precise way.

Data characterizationSummarize the data of the class under study (target class)

Data Discrimination Compare the target class with a set of comparative classes (contrasting classes)

Data characterization & Discrimination Perform both analysis

Example of data from a storeClasses Concepts

printers computers Big-Spenders Budget-Spenders

Characterization and Discrimination (2)

Data CharacterizationSummarize the general features of a target class of dataTools: statistical measures, data cube-based OLAP roll-up, etc.Output: charts, curves, multidimensional data cubes, etc. Example

Data Discrimination Comparison of the general features of a target class with the general features of contrasting classesOutput: similar to characterization + comparative measuresExample

Summarize the characteristics of costumers who spend more than 1000€

• 40-50 years old• Employed• excellent credit ratings

Costumers profile

Compare customers who shop for computer products regularly( more than 2 times a month) with those who rarely shop for such products(less then three times a year)

Comparative profileFrequent costumers

Rare costumers

80% •Are between 20 and 40•Have university education

60%•Are senior or youths•Have no university degree

Frequent Patterns, Associations, Correlations

Frequent patterns are patterns occurring frequently in the data (e.g., item-sets, sub-sequences, and substructures)

Frequent item-sets: items that frequently appear together Example in a transactional data set: bred and milk

Frequent Sequential pattern: a frequently occurring subsequenceExample in a transactional data set: buy first PC, second digital camera, third memory card

Association AnalysisDerive some association rules

buys(X, “computer”) ⇒ buys (X, “software”) [support =1%, confidence=50%]age(X, “20...29” ) ∧ income(X, “20K...29K”) ⇒ buys (X, “CD player”)[support =2%, confidence=60%]

Correlation Analysis Uncover interesting statistical correlations between associated attribute-value pairs

Classification and Prediction

Construct models (functions) based on some training examplesDescribe and distinguish classes or concepts for future predictionPredict some unknown class labels

Typical methodsDecision trees, naive Bayesian classification, logistic regression, support vector machine, neural networks, etc.

Typical ApplicationsCredit card fraud detection, classifying web pages, stars, diseases, etc.

Age Income Class label

27 28K Budget-Spenders

35 36K Big-Spenders

65 45K Budget-Spenders

Supervised Learning

Classificationmodel (function)

Trainingexamples

Classifier

Class label

Numeric valueUnlabeled data

Age Income 29 25K

[Budget Spender]

[Budget Spender (0.8)]

Cluster Analysis

Unsupervised learning (i.e., Class label is unknown)Group data to form new categories (i.e., clusters), e.g., cluster houses to find distribution patternsPrinciple: Maximizing intra-class similarity & minimizing interclass similarity

Typical methodsHierarchical methods, density-based methods, Grid-based methods, Model-Based methods, constraint-based methods, etc.

Typical ApplicationsWWW, social networks, Marketing, Biology, Library, etc.

Outlier Analysis

Outlier: A data object that does not comply with the general behavior of the data learning (i.e., Class label is unknown)Noise or exception? ― One person’s garbage could be another person’s treasure

Typical methodsProduct of clustering or regression analysis, etc.

Typical ApplicationsUseful in fraud detectionExample

How to Uncover fraudulent usage of credit card?Detect purchases of extremely large amounts for a given account number in comparison to regular charges incurred by the same accountOutliers may also be detected with respect to the location and type of purchase, or the frequency.

Or ?

Evolution Analysis

Evolution Analysis describes trends of data objects whose behavior changes over timeIt includes

Characterization and discrimination analysisAssociation and correlation analysisClassification and predictionClustering of time–related data

Distinct features for such analysisTime-series data analysisSequence or periodicity pattern matching

e.g., first buy digital camera, then buy large SD memory cardsSimilarity-based analysis

1.1.4 Techniques Utilized

Data-intensiveData warehouse (OLAP)Machine learningStatistics Pattern recognitionVisualizationHigh-performance...

1.1.5 Applications Adapted

Web page analysis: from web page classification, clustering to PageRank & HITS algorithms

Collaborative analysis & recommender systems

Basket data analysis to targeted marketing

Biological and medical data analysis: classification, cluster analysis (microarray data analysis), biological sequence analysis, biological network analysis

From major dedicated data mining systems/tools (e.g., SAS, MS SQL-Server Analysis Manager, Oracle Data Mining Tools) to invisible data mining

1.1.6 Major Challenges in Data Mining

Efficiency and scalability of data mining algorithms

Parallel, distributed, stream, and incremental mining methods

Handling high-dimensionality

Handling noise, uncertainty, and incompleteness of data

Incorporation of constraints, expert knowledge, and background knowledge in data mining

Pattern evaluation and knowledge integration

Mining diverse and heterogeneous kinds of data: e.g., bioinformatics, Web, software/system engineering, information networks

Application-oriented and domain-specific data mining

Invisible data mining (embedded in other functional modules)

Protection of security, integrity, and privacy in data mining

Summary of Section 1.1Data Mining is a process of extracting knowledge from dataData to be mined can be of any type

Relational Databases, Advanced databases, etc.Knowledge to be discovered

Frequent patterns, correlations, associations, classification, prediction, clustering

Techniques to be usedStatistics, machine learning, visualization, etc.

Data Mining is interdisciplinary Large amount of complex data and sophisticated applications

Challenges of data MiningEfficiency, scalability, parallel and distributed mining, handling high dimensionality, handling noisy data, mining heterogeneous data, etc.