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Data Mining

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Syllabus Week Material• Week Introduction• Week 2 Data Warehouse & OLAP• Week 3 Data Preprocessing• Week 4 Data Mining Languages• Week 5 Concept Description • Week 6 Statistic• Week 7-8 Association Rules• Week 9-10 Classification• Week 11-12 Cluster Analysis• Week 13-14 Mining Complex Data• Week 15 Applications

• Midterm 3/2/04

• Project due 4/29/04

• Final 5/6/04

• No Late Submissions are allowed

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Textbook and Other Reading Materials

• Textbook: Data Mining: Concepts and Techniques by Jiawei Han and Micheline Kamber, Morgan Kaufman, 2001

• Other texts that I may use from time to time:– Data Mining –Introductory and Advanced Topics by

Margaret H. Duhnam, Pearson Education,Inc, 2003– Principles of Data Mining by David Hand, Heikki Mannila, and

Padhriac Smyth, MIT Press 2001

• Papers: VLDB, SIGMOD, and SIGKDD Proceedings`

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Introduction

• Motivation.

• What is data mining?

• Data mining functionality

• Are all the patterns interesting?

• Classification of data mining systems

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Motivation:

• Huge amount of databases and web pages make information

extraction next to impossible (remember the favored statement: I

will bury them in data!)

• Inability of many other disciplines: (statistic, AI, information

retrieval) to have scalable algorithms to extract information

and/or rules from the databases

• Necessity to find relationships among data

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Appetizer

• Consider a file consisting of 24471 records. File contains at least two condition attributes: A and D

A/D 0 1 total

0 9272 232 9504

1 14695 272 14967

Total 23967 504 24471

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Appetizer (con’t)• Probability that person has A: P(A)=0.6, P(D)=0.02• Conditional probability that person has D provided it has A: P(D|

A) = P(AD)/P(A)=(272/24471)/.6 = .02• P(A|D) = P(AD)/P(D)= .56• What can we say about dependencies between A and D?

A/D 0 1 total

0 9272 232 9504

1 14695 272 14967

Total 23967 504 24471

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Appetizer(3)

• So far we did not ask anything that statistics would not have ask. So Data Mining another word for statistic?

• We hope that the response will be resounding NO • The major difference is that statistical methods work

with random data samples, whereas the data in databases is not necessarily random

• The second difference is the size of the data set• The third data is that statistical samples do not

contain “dirty” data

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STATISTIC is NOT DATA MINING

• Originally data mining was a statistician term for overusing data to create possible wrong inferences.

• Famous example of wrong inferences is in parapsychology on ECP (extrasensory perception)

• If there are too many conclusions from the data, then some will be certainly true.

• Data Mining is a discovery of UNEXPECTED data correlations

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What Is Data Mining?

• Data mining (knowledge discovery in databases): – Extraction of interesting information or patterns from data in

large databases

• Alternative names and their “inside stories”: – Knowledge discovery(mining) in databases (KDD),

knowledge extraction, data/pattern analysis, data archeology, data dredging, information harvesting, business intelligence, etc.

• What is not data mining?– (Deductive) query processing. – Expert systems or small ML/statistical programs– Statistics– Artificial Intelligence

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Data Mining: Process

– Data mining: the core of knowledge discovery process.

Data Cleaning

Data Integration

Databases

Data Warehouse

Task-relevant Data

Selection

Data Mining

Pattern Evaluation

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What Is Data Mining – Steps in the DM Process

• Data cleaning, noise removal• Data Integration- data warehousing techniques,

OLAP• Data Relevancy decision• Data Transformation (data qube, aggregation and

summarization)• Pattern evaluations• Results presentation

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What is DM: Potential Applications

• Database analysis and decision support

– Market analysis and management

• target marketing, customer relation management, market basket

analysis, cross selling, market segmentation

– Risk analysis and management

• Forecasting, customer retention, improved underwriting, quality

control, competitive analysis

– Fraud detection and management

• Other Applications

– Text mining (news group, email, documents) and Web analysis.

– Intelligent query answering

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Market Analysis and Management (1)

• Where are the data sources for analysis?– Credit card transactions, loyalty cards, discount coupons,

customer complaint calls, plus (public) lifestyle studies

• Target marketing– Find clusters of “model” customers who share the same

characteristics: interest, income level, spending habits, etc.

• Determine customer purchasing patterns over time– Conversion of single to a joint bank account: marriage, etc.

• Cross-market analysis– Associations/co-relations between product sales

– Prediction based on the association information

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Market Analysis and Management (2)

• Customer profiling

– data mining can tell you what types of customers buy what

products (clustering or classification)

• Identifying customer requirements

– identifying the best products for different customers

– use prediction to find what factors will attract new customers

• Provides summary information

– various multidimensional summary reports

– statistical summary information (data central tendency and

variation)

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Corporate Analysis and Risk Management

• Finance planning and asset evaluation– cash flow analysis and prediction– contingent claim analysis to evaluate assets – cross-sectional and time series analysis (financial-ratio, trend

analysis, etc.)

• Resource planning:– summarize and compare the resources and spending

• Competition:– monitor competitors and market directions – group customers into classes and a class-based pricing

procedure– set pricing strategy in a highly competitive market

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Fraud Detection and Management (1)

• Applications– widely used in health care, retail, credit card services,

telecommunications (phone card fraud), etc.

• Approach– use historical data to build models of fraudulent behavior and

use data mining to help identify similar instances

• Examples– auto insurance: detect a group of people who stage accidents to

collect on insurance– money laundering: detect suspicious money transactions (US

Treasury's Financial Crimes Enforcement Network) – medical insurance: detect professional patients and ring of

doctors and ring of references

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Fraud Detection and Management (2)

• Detecting inappropriate medical treatment• Detecting telephone fraud

– Telephone call model: destination of the call, duration, time of day or week. Analyze patterns that deviate from an expected norm.

– British Telecom identified discrete groups of callers with frequent intra-group calls, especially mobile phones, and broke a multimillion dollar fraud.

• Retail– Analysts estimate that 38% of retail shrink is due to

dishonest employees.

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Other Applications

• Sports– IBM Advanced Scout analyzed NBA game statistics (shots

blocked, assists, and fouls) to gain competitive advantage for New York Knicks and Miami Heat

• Astronomy– JPL and the Palomar Observatory discovered 22 quasars with

the help of data mining

• Internet Web Surf-Aid– IBM Surf-Aid applies data mining algorithms to Web access

logs for market-related pages to discover customer preference and behavior pages, analyzing effectiveness of Web marketing, improving Web site organization, etc.

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Architecture of a Typical Data Mining System

Data Warehouse

Data cleaning & data integration Filtering

Databases

Database or data warehouse server

Data mining engine

Pattern evaluation

Graphical user interface

Knowledge-base

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Data Mining System Architecture

• Database, data warehouse, data files- set of data to be mined. Data Cleaning and data integration may be performed at this stage

• Database or data warehouse server is responsible for fetching relevant data. How to define relevancy?

• Knowledge Base – Domain knowledge that drives a search for patterns. Concept hierarchy, User Beliefs, Interestingness Constraints

• Data Mining Engine-Functional algorithms to perform a search for domain experts

• Pattern Evaluation – Use knowledge base and other methods to narrow search for domain patters

• GUI – Communicator between users and data mining system

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Data Mining: On What Kind of Data?

• Relational databases – Universal relation vs Multirelational search

• Data warehouses• Transactional databases• Advanced DB and information repositories

– Object-oriented and object-relational databases– Spatial databases– Time-series data and temporal data– Text databases and multimedia databases– Heterogeneous and legacy databases– WWW

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Data Mining: On What Kind of Data?

• Attribute Types: – Categorical – attribute that has a finite number of values– Ordinal – attributes can be ordered by their values

• Attribute Transformations:– Continuing - attribute that may have infinite but countable set of

values. These attributes always can be ordered– Interval scale– Boolean

• Nominal – attributes that cannot be ordered by their values

– Operational - example measurement of programming productivity as am(n+m)log(a+b)/2b, where a is the number of unique operators,b is the number of unique operands, n-number of total operators occurences and m the number of total operands occurences

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Data Mining Tasks

• Association (correlation and causality)– Multi-dimensional vs. single-dimensional association

– age(X, “20..29”) ^ income(X, “20..29K”) -> buys(X, “PC”) [support = 2%, confidence = 60%]

– contains(T, “computer”) -> contains(x, “software”) [1%, 75%]

– What is support? – the percentage of the tuples in the database that have age between 20 and 29 and income between 20K and 29K and buying PC

– What is confidence? – the probability that if person is between 20 and 29 and income between 20K and 29K then it buys PC

• Clustering (getting data that are close together into the same cluster.

• What does “close together” means?

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Distances between data

• Distance between data is a measure of dissimilarity between data.d(i,j)>=0; d(i,j) = d(j,i); d(i,j)<= d(i,k) + d(k,j)

• Euclidean distance: <x1,x2, … xk> and <y1,y2,…yk>

• Standardize variables by finding standard deviation and dividing each xi by standard deviation of X

• Covariance(X,Y)=1/k(Sum(xi-mean(x))(y(I)-mean(y))

• Boolean variables and their distances

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Data Mining Tasks

• Outlier analysis– Outlier: a data object that does not comply with the general behavior of

the data

– It can be considered as noise or exception but is quite useful in fraud

detection, rare events analysis

• Trend and evolution analysis

– Trend and deviation: regression analysis

– Sequential pattern mining, periodicity analysis

– Similarity-based analysis

• Other pattern-directed or statistical analyses

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Are All the “Discovered” Patterns Interesting?

• A data mining system/query may generate thousands of patterns,

not all of them are interesting.

– Suggested approach: Human-centered, query-based, focused mining

• Interestingness measures: A pattern is interesting if it is easily

understood by humans, valid on new or test data with some degree

of certainty, potentially useful, novel, or validates some hypothesis

that a user seeks to confirm

• Objective vs. subjective interestingness measures:

– Objective: based on statistics and structures of patterns, e.g., support,

confidence, etc.

– Subjective: based on user’s belief in the data, e.g., unexpectedness,

novelty, actionability, etc.

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Are All the “Discovered” Patterns Interesting? - Example

1

tea

coffee

0 70 755

5 20 25

0 1

Conditional probability that if one buys coffee, one also buys teais 2/9Conditional probability that if one buys tea she also buys coffeeis 20/25=.8However, the probability that she buys coffee is .9So, is it significant inference that if customer buys tea she also buys coffee?Is buying tea and coffee independent activities?

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How to measure Interestingness

• RI = | X , Y| - |X||Y|/N

• Support and Confidence: |X Y|/N – support and |X Y|/|X| -

confidence of X->Y

• Chi^2: (|XY| - E(|XY|)) ^2 /E(|XY|);

• J(X->Y) = P(Y)(P(X|Y)*log (P(X|Y)/P(X)) + (1- P(X|Y))*log ((1- P(X|

Y)/(1-P(X))

• Sufficiency (X->Y) = P(X|Y)/P(X|!Y); Necessity (X->Y) = P(!X|Y)/P(!

X|!Y). Interestingness of Y->X is

NC++ = 1-N(X->Y)*P(Y), if N(…) is less than 1 or 0 otherwise

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Can We Find All and Only Interesting Patterns?

• Find all the interesting patterns: Completeness– Can a data mining system find all the interesting patterns?

– Association vs. classification vs. clustering

• Search for only interesting patterns: Optimization– Can a data mining system find only the interesting patterns?

– Approaches

• First general all the patterns and then filter out the uninteresting

ones.

• Generate only the interesting patterns—mining query optimization

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A Multi-Dimensional View of Data Mining Classification

• Databases to be mined– Relational, transactional, object-oriented, object-relational,

active, spatial, time-series, text, multi-media, heterogeneous, legacy, WWW, etc.

• Knowledge to be mined– Characterization, discrimination, association, classification,

clustering, trend, deviation and outlier analysis, etc.– Multiple/integrated functions and mining at multiple levels

• Techniques utilized– Database-oriented, data warehouse (OLAP), machine learning,

statistics, visualization, neural network, etc.• Applications adapted

– Retail, telecommunication, banking, fraud analysis, DNA mining, stock market analysis, Web mining, Weblog analysis, etc.

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OLAP Mining: An Integration of Data Mining and Data Warehousing

• Data mining systems, DBMS, Data warehouse

systems coupling– No coupling, loose-coupling, semi-tight-coupling, tight-coupling

• On-line analytical mining data– integration of mining and OLAP technologies

• Interactive mining multi-level knowledge– Necessity of mining knowledge and patterns at different levels of

abstraction by drilling/rolling, pivoting, slicing/dicing, etc.

• Integration of multiple mining functions– Characterized classification, first clustering and then association

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An OLAM Architecture

Data Warehouse

Meta Data

MDDB

OLAMEngine

OLAPEngine

User GUI API

Data Cube API

Database API

Data cleaning

Data integration

Layer3

OLAP/OLAM

Layer2

MDDB

Layer1

Data Repository

Layer4

User Interface

Filtering&Integration Filtering

Databases

Mining query Mining result

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Major Issues in Data Mining (1)

• Mining methodology and user interaction– Mining different kinds of knowledge in databases

– Interactive mining of knowledge at multiple levels of abstraction

– Incorporation of background knowledge

– Data mining query languages and ad-hoc data mining

– Expression and visualization of data mining results

– Handling noise and incomplete data

– Pattern evaluation: the interestingness problem

• Performance and scalability– Efficiency and scalability of data mining algorithms

– Parallel, distributed and incremental mining methods

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Major Issues in Data Mining (2)

• Issues relating to the diversity of data types– Handling relational and complex types of data– Mining information from heterogeneous databases and global

information systems (WWW)

• Issues related to applications and social impacts– Application of discovered knowledge

• Domain-specific data mining tools

• Intelligent query answering

• Process control and decision making

– Integration of the discovered knowledge with existing knowledge: A knowledge fusion problem

– Protection of data security, integrity, and privacy

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Summary

• Data mining: discovering interesting patterns from large amounts of data

• A natural evolution of database technology, in great demand, with wide applications

• A KDD process includes data cleaning, data integration, data selection, transformation, data mining, pattern evaluation, and knowledge presentation

• Mining can be performed in a variety of information repositories

• Data mining functionalities: characterization, discrimination, association, classification, clustering, outlier and trend analysis, etc.

• Classification of data mining systems

• Major issues in data mining