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Data Mining : Intelligent Data Analysis for Knowledge Discovery Prof. Yike Guo Dept. of Computing Imperial College Intelligent Data Analysis and Probability Inference Course Overview • Goal – Basic Concepts of Data Mining – Data Mining Techniques – Data Mining Applications – Future Research Trends on Data Mining • Reference Books • Data Mining: Concepts and Techniques JiaWei Han and Micheline Kamber • Advances in Knowledge Discovery and Data Mining U.M Fayyad and G, Piatetsky-Shapiro AAAI/MIT Press. 1996 • Predictive Data Mining: A Practical Guide Sholom M.Weiss and Nitin Indurkhya Morgan Kaufmann Publishers, Inc. 1997 • Intelligent Data Analysis, Springer 1999 • Post-genome Informatics by Minoru Kanehisa, Oxford University Press, 2000 Intelligent Data Analysis and Probability Inference What does the data say? Day Outlook Temperature 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Sunny Sunny Overcast Rain Rain Rain Overcast Sunny Sunny Rain Sunny Overcast Overcast Rain Hot Hot Hot Mild Cool Cool Cool Mild Cool Mild Mild Mild Hot Mild Humidity High High High High Normal Normal Normal High Normal Normal Normal High Normal High Wind Play Tennis Weak Strong Weak Weak Weak Strong Strong Weak Weak Weak Strong Strong Weak Strong No No Yes Yes Yes No Yes No Yes Yes Yes Yes Yes No Intelligent Data Analysis and Probability Inference Turing Data into Knowledge Intelligent Data Analysis and Probability Inference What does the data say? 100 000 10 000 1000 Amount (x1000) 100 10 1 0.1 MEDLINE records MEDLINE G5 MeSH Transistors / chip DNA sequences Mapped human genes 3-D structures 0.01 0.001 1965 1970 1975 1980 1985 1990 1995 2000 Year Intelligent Data Analysis and Probability Inference Intelligent Data Analysis and Probability Inference What Is Data Mining? • Data mining (knowledge discovery in databases): – Extraction of interesting (non-trivial, implicit, previously unknown and potentially useful) information or patterns from data in large databases • Alternative names and their “inside stories”: – Data mining: a misnomer? – 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 Intelligent Data Analysis and Probability Inference • Data: set of facts F ( records in a database) • Pattern : An expression E in a language L describing data in a subset FE of F and E is simpler than the enumeration of al l the facts of FE. FE is also called a class and E is also called a model or knowledge. • Data Mining Process: data mining is a multi-step process involving multiple choices, iteration and evaluation. It is nontrivial since there is no closed-form solution. It always involve intensive search. • Validity : E is true (with high probability) for F • Useful : patterns are not trivial inductive properties of data • Understandable: patterns should be understandable by data owners to aid in understanding the data/domain Intelligent Data Analysis and Probability Inference Why Data Mining • Limitation of traditional database querying: – Most queries of interest to data owners are difficult to state in a query language • “ find me all records indicating fraud”=> “ tell me the characteristics of fraud” (Summarisation) • “find me who likely to buy product X” (classification problem) • “find all records that are similar to records in table X” (clustering problem) – Ability to support analysis and decision making using traditional (SQL) queries become infeasible (query formulation problem ). Intelligent Data Analysis and Probability Inference Relational Database Revisited • Terabyte databases, consisting of billions of records, are becoming common • Relational data model is the defacto standard • A relational database : set of relations • A relation : a set of homogenous tuples • Relations are created, updated and queried using SQL • Query = Keyword based search SELECT telephone_number FROM telephone_book WHERE last_name = “Smith” Intelligent Data Analysis and Probability Inference SQL : Relational Querying Language • Provides a well-defined set of operations: scan, join, insert, delete, sort, aggregate, union, difference • Scan -- applies a predicate P to relation R For each tuple tr from R if P(tr) is true, tr is inserted in the output stream • Join -- composes two relations R and S For each tuple tr from R For each tuple ts from S if join attribute of tr equals to join attribute of ts form output tuple by concatenating tr and ts Intelligent Data Analysis and Probability Inference Pages MUID Relational database. A table (relation) is a set and the three basic table operations shown here are extensions of the standard set operations. Paper 1 Paper 2 Paper 3 Paper 4 .... SELECT Author MUID Author Pages MUID PROJECT JOIN Author 1-1 Author 1-2 Author 2-1 Author 2-2 Author 2-3 Author 3-1 .... Intelligent Data Analysis and Probability Inference The Query Formulation Problem Consider the query : What kinds of weather condition are suitable for playing tennis ? • It is not solvable via query optimisation • Has not received much attention in the database field or in traditional statistical approaches • These problems are of inductive features: learning from data rather than search from data • Natural solution is via train-by-example approach to construct inductive models as the answers Intelligent Data Analysis and Probability Inference Why Data Mining Now • Data Explosion – Business Data : organisations such as supermarket chains, credit card companies, investment banks, government agencies, etc. routinely generate daily volumes of 100MB of data – Scientific Data: Scientific and remote sensing instruments collect data at the rates of Gigabytes per day: far beyond human analysis abilities. • Data Wasting – Only a small portion (5% - 10%) of the collected data is ever analysed – Data that may never be analysed continues to be collected, at great expense. • We are drowning in data, but starving for knowledge! Intelligent Data Analysis and Probability Inference Steps of a KDD Process • Learning the application domain: – relevant prior knowledge and goals of application • Creating a target data set: data selection • Data cleaning and preprocessing: (may take 60% of effort!) • Data reduction and transformation: – Find useful features, dimensionality/variable reduction, invariant representation. • Choosing functions of data mining – summarization, classification, regression, association, clustering. • Choosing the mining algorithm(s) • Data mining: search for patterns of interest • Pattern evaluation and knowledge presentation – visualization, transformation, removing redundant patterns, etc. • Use of discovered knowledge Intelligent Data Analysis and Probability Inference Data Mining and Decision Support Data Warehousing: create/ select target database Sampling: choose data for building models Data Reduction and Projection: derive useful features dimensionality reduction Data Cleaning: supply missing values eliminate noisy data Data Mining: choose data mining tasks choose data mining methods to extract patterns / knowledge Model Test and Evaluation: test the accuracy of the model consistency check model refinement Machine Learning Technologies Decision SupportData Analysis and Probability Inference Intelligent Data Warehousing • “ A data warehouse is a subject-oriented, integrated, time-variant, and nonvolatile collection of data in support of management’s decision-making process.” --- W. H. Inmon • A data warehouse is – A decision support database that is maintained separately from the organization’s operational databases. – It integrates data from multiple heterogeneous sources to support the continuing need for structured and /or ad-hoc queries, analytical reporting, and decision support. Intelligent Data Analysis and Probability Inference Modeling Data Warehouses • Modeling data warehouses: dimensions & measurements – Star schema: A single object (fact table) in the middle connected to a number of objects (dimension tables) radically. – Snowflake schema: A refinement of star schema where the dimensional hierarchy is represented explicitly by normalizing the dimension tables. – Fact constellations: Multiple fact tables share dimension tables. • Storage of selected summary tables: – Independent summary table storing pre-aggregated data, e.g., total sales by product by year. – Encoding aggregated tuples in the same fact table and the same dimension tables. Intelligent Data Analysis and Probability Inference Example of Star Schema Time Dimension Table Sales Fact Table Product Dimension Table Many Time Attributes Time_Key Many Product Attributes Product_Key Store Dimension Table Many Store Attributes Store_Key Location_Key Location Dimension Table Many Location Attributes unit_sales Measures dollar_sales Yen_sales Intelligent Data Analysis and Probability Inference OLAP: On-Line Analytical Processing • A multidimensional, LOGICAL view of the data. • Interactive analysis of the data: drill, pivot, slice_dice, filter. • Summarization and aggregations at every dimension intersection. • Retrieval and display of data in 2-D or 3-D crosstabs, charts, and graphs, with easy pivoting of the axes. • Analytical modeling: deriving ratios, variance, etc. and involving measurements or numerical data across many dimensions. • Forecasting, trend analysis, and statistical analysis. • Requirement: Quick response to OLAP queries. Intelligent Data Analysis and Probability Inference OLAP Architecture • Logical architecture: – OLAP view: multidimensional and logic presentation of the data in the data warehouse/mart to the business user. – Data store technology: The technology options of how and where the data is stored. • Three services components: – data store services – OLAP services, and – user presentation services. • Two data store architectures: – Multidimensional data store: (MOLAP). – Relational data store: Relational OLAP (ROLAP). Intelligent Data Analysis and Probability Inference Multidimensional Data • Sales volume as a function of product, month, and region Dimensions: Product, Location, Time Hierarchical summarization paths Industry Region Year Product Category Country Quarter Product City Office Month Month Week Day Intelligent Data Analysis and Probability Inference Construction of Data Cubes Amount B.C. Province Prairies Ontario sum 0-20K20-40K 40-60K60K- sum All Amount Comp_Method, B.C. Comp_Method Database … ... Discipline sum Each dimension contains a hierarchy of values for one attribute A cube cell stores aggregate values, e.g., count, sum, max, etc. A “sum” cell stores dimension summation values. Sparse-cube technology and MOLAP/ROLAP integration. “Chunk”-based multi-way aggregation and single-pass computation. Intelligent Data Analysis and Probability Inference A Star-Net Query Model Customer Orders Shipping Method Customer CONTRACTS AIR-EXPRESS ORDER TRUCK PRODUCT LINE Time Product ANNUALY QTRLY DAILY PRODUCT ITEM PRODUCT GROUP DISTRICT SALES PERSON REGION DISTRICT COUNTRY DIVISION Geography Promotion Organization Intelligent Data Analysis and Probability Inference Decision Support with Data Warehouse • Ad Hoc Queries: Q: How many customers do we have in London? A: 32776 Intelligent Data Analysis and Probability Inference • Report and Spreadsheet Intelligent Data Analysis and Probability Inference • OLAP: Q:What are the sales figures for Y in the different regions: Intelligent Data Analysis and Probability Inference • Statistics: Q: Is there a relation between age and buy behaviour? A: Older clients buy more Intelligent Data Analysis and Probability Inference • Data Mining: Q: What factors influence buying behaviour ? A1: : Young men in sports cars buy 3 times as much audio equipment (clustering/regression): Age A2: Older woman with dark hair more often buy rinse (classification) Old Hair color B A3: Buyers of cars are also the buyers of houses (asociation) Young Middle Y Wage N W L N N H Y Intelligent Data Analysis and Probability Inference Data Mining Functionalities (1) • Concept description: Characterization and discrimination – Generalize, summarize, and contrast data characteristics, e.g., dry vs. wet regions • Association (correlation and causality) – Multi-dimensional vs. single-dimensional association – age(X, “20..29”) ^ income(X, “20..29K”) à buys(X, “PC”) [support = 2%, confidence = 60%] – contains(T, “computer”) à contains(x, “software”) [1%, 75%] Intelligent Data Analysis and Probability Inference Data Mining Functionalities (2) • Classification and Prediction – Finding models (functions) that describe and distinguish classes or concepts for future prediction – E.g., classify countries based on climate, or classify cars based on gas mileage – Presentation: decision-tree, classification rule, neural network – Prediction: Predict some unknown or missing numerical values • Cluster analysis – Class label is unknown: Group data to form new classes, e.g., cluster houses to find distribution patterns – Clustering based on the principle: maximizing the intra-class similarity and minimizing the interclass similarity Intelligent Data Analysis and Probability Inference Data Mining Functionalities (3) • 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 Intelligent Data Analysis and Probability Inference Example Data Mining Applications • Commercial : – – – – Fraud detection: Identify Fraudulent transaction Loan approval: Establish the credit worthiness of a customer requesting a loan Investment analysis : Predict a portfolio's return on investment Marketing and sales data analysis: Identify potential customers; establishing the effectiveness of a sales campaign • Medical: – Drug effect analysis : from patient records to learn drug effects – Disease causality analysis • Political policy: – Election policy : people’s voting patterns – Social policy: tax/benefit policy • Manufacturing: – Manufacturing process analysis: identify the causes of manufacturing problems – Experiment result analysis : Summarise experiment results and create predictive models Intelligent Data Analysis and Probability Inference 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 Intelligent Data Analysis and Probability Inference 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) Intelligent Data Analysis and Probability Inference 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 Intelligent Data Analysis and Probability Inference Fraud Detection and Management (2) • Detecting inappropriate medical treatment – Australian Health Insurance Commission identifies that in many cases blanket screening tests were requested (save Australian $1m/yr). • 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. Intelligent Data Analysis and Probability Inference Related Fields: • Machine learning: Inductive reasoning • Statistics : Sampling, Statistical Inference, Error Estimation • Pattern recognition: Neural Networks, Clustering • Knowledge Acquisition, Statistical Expert Systems • Data Visualisation • Databases: OLAP, Parallel DBMS, Deductive Databases • Data Warehousing: collection, cleaning of transactional data for on-line retrial Intelligent Data Analysis and Probability Inference