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Data Warehouse and Business Intelligence Dr. Minder Chen [email protected] Fall 2008 Online Resources • Additional resources: – Teradata Student Network. » The Premier Learning Resource for Data Warehousing, DSS/BI, and Database. The URL is http://www.teradatastudentnetwork.com » PSW: smartdecisions © Minder Chen, 2004-2008 Data Warehouse - 2 BI Business Intelligence (BI) is the process of gathering meaningful information to answer questions and identify significant trends or patterns, giving key stakeholders the ability to make better business decisions. “The key in business is to know something that nobody else knows.” -- Aristotle Onassis PHOTO: HULTON-DEUTSCH COLL “To understand is to perceive patterns.” — Sir Isaiah Berlin "The manager asks how and when, the leader asks what and why." — “On Becoming a Leader” by Warren Bennis © Minder Chen, 2004-2008 Data Warehouse - 3 BI Questions • What happened? – What were our total sales this month? • What’s happening? – Are our sales going up or down, trend analysis • Why? – Why have sales gone down? • What will happen? – Forecasting & “What If” Analysis • What do I want to happen? – Planning & Targets Source: Bill Baker, Microsoft © Minder Chen, 2004-2008 Data Warehouse - 4 Business Intelligence Increasing potential to support business decisions (MIS) Making Decisions Data Presentation Visualization Techniques End User Business Analyst Data Analyst Data Mining Information Discovery Data Exploration OLAP, MDA, Statistical Analysis, Querying and Reporting Data Warehouses / Data Marts Data Sources (Paper, Files, Information Providers, Database Systems, OLTP) © Minder Chen, 2004-2008 DBA Data Warehouse - 5 Where is Business Intelligence applied? Operational Efficiency • • • • • • • • ERP Reporting KPI Tracking Product Profitability Risk Management Balanced Scorecard Activity Based Costing Global Sourcing Logistics © Minder Chen, 2004-2008 Customer Interaction • • • • • • • Sales Analysis Sales Forecasting Segmentation Cross-selling CRM Analytics Campaign Planning Customer Profitability Data Warehouse - 6 © Minder Chen, 2004-2008 Data Warehouse - 7 Inmon's Definition of Data Warehouse – Data View • A warehouse is a – subject-oriented, – integrated, – time-variant and – non-volatile collection of data in support of management's decision making process. Source: http://www.intranetjournal.com/features/datawarehousing.html – Bill Inmon in 1990 © Minder Chen, 2004-2008 Data Warehouse - 8 Inmon's Definition Explain • Subject-oriented: They are organized around major subjects such as customer, supplier, product, and sales. Data warehouses focus on modeling and analysis to support planning and management decisions v.s. operations and transaction processing. • Integrated: Data warehouses involve an integration of sources such as relational databases, flat files, and online transaction records. Processes such as data cleansing and data scrubbing achieve data consistency in naming conventions, encoding structures, and attribute measures. • Time-variant: Data contained in the warehouse provide information from an historical perspective. • Nonvolatile: Data contained in the warehouse are physically separate from data present in the operational environment. © Minder Chen, 2004-2008 Data Warehouse - 9 Kimball's Definition – Process View • A data warehouse is a system that extracts, cleans, conforms, and delivers source data into a dimensional data store and then supports and implements querying and analysis for the purpose of decision making. » Ralph Kimball © Minder Chen, 2004-2008 Data Warehouse - 10 © Minder Chen, 2004-2008 Data Warehouse - 11 The Data Warehouse Process Data Marts and cubes Source Systems Clients Data Warehouse 1 Design the Data Warehouse © Minder Chen, 2004-2008 2 Populate Data Warehouse Query Tools Reporting Analysis Data Mining 3 Create OLAP Cubes 4 Query Data Data Warehouse - 12 Key Concepts in BI Development Lifecycle © Minder Chen, 2004-2008 Data Warehouse - 13 Business Valuation Models for BI © Minder Chen, 2004-2008 Data Warehouse - 14 Performance Dashboards for Information Delivery © Minder Chen, 2004-2008 Data Warehouse - 15 Scorecards for Information Delivery © Minder Chen, 2004-2008 Data Warehouse - 16 OLTP Normalized Design Warehouse Ordering Process Chain Retailer Store Retailer Payments Retailer Returns Product POS Process Retail Promo Brand GL Account Retail Cust Cash Register © Minder Chen, 2004-2008 Clerk Data Warehouse - 17 OLTP Versus Business Intelligence: Who asks what? OLTP Questions • When did that order ship? • How many units are in inventory? • Does this customer have unpaid bills? • Are any of customer X’s line items on backorder? © Minder Chen, 2004-2008 Analysis Questions • What factors affect order processing time? • How did each product line (or product) contribute to profit last quarter? • Which products have the lowest Gross Margin? • What is the value of items on backorder, and is it trending up or down over time? Data Warehouse - 18 OLTP vs. OLAP Source: http://www.rainmakerworks.com/pdfdocs/OLTP_vs_OLAP.pdf#search=%22OLTP%20vs.%20OLAP%22 © Minder Chen, 2004-2008 Data Warehouse - 19 Dimensional Design Process Business Requirements • Select the business process to model • Declare the grain of the business process/data in the fact table • Choose the dimensions that apply to each fact table row • Identify the numeric facts that will populate each fact table row Data Realities © Minder Chen, 2004-2008 Data Warehouse - 20 Select a business process to model • Not business departments or business functions • Cross-functional business processes • Business events • Examples: – – – – – – Raw materials purchasing Order fulfillment process Shipments Invoicing Inventory General ledger © Minder Chen, 2004-2008 Data Warehouse - 21 Requirements © Minder Chen, 2004-2008 Data Warehouse - 22 Identifying Measures and Dimensions Performance Measures for KPI Measures Performance Drivers Dimensions The attribute varies continuously: The attribute is perceived as a constant or discrete value: •Balance •Unit Sold •Cost •Sales •Description •Location •Color •Size © Minder Chen, 2004-2008 Data Warehouse - 23 A Dimensional Model for a Grocery Store Sales © Minder Chen, 2004-2008 Data Warehouse - 24 Product Dimension • SKU: Stock Keeping Unit • Hierarchy: – Department Category Subcategory Brand Product © Minder Chen, 2004-2008 Data Warehouse - 25 Creating Dimensional Model • Identify fact tables • Translate business measures into fact tables • Analyze source system information for additional measures • Identify base and derived measures • Document additivity of measures • Identify dimension tables • Link fact tables to the dimension tables • Create views for users © Minder Chen, 2004-2008 Data Warehouse - 26 Transaction Level Order Item Fact Table © Minder Chen, 2004-2008 Data Warehouse - 27 Inside a Dimension Table • Dimension table key: Uniquely identify each row. Use surrogate key (integer). • Table is wide: A table may have many attributes (columns). • Textual attributes. Descriptive attributes in string format. No numerical values for calculation. • Attributes not directly related: E.g., product color and product package size. No transitive dependency. • Not normalized (star schemar). • Drilling down and rolling up along a dimension. • One or more hierarchy within a dimension. • Fewer number of records. © Minder Chen, 2004-2008 Data Warehouse - 28 Fact Tables Fact tables have the following characteristics: • Contain numeric measures (metric) of the business • May contain summarized (aggregated) data • May contain date-stamped data • Are typically additive • Have key value that is typically a concatenated key composed of the primary keys of the dimensions • Joined to dimension tables through foreign keys that reference primary keys in the dimension tables © Minder Chen, 2004-2008 Data Warehouse - 29 Facts Table Measurements of business events. DateID ProductID Dimensions CustomerID Units Dollars Measures The Fact Table contains keys and units of measure © Minder Chen, 2004-2008 Data Warehouse - 30 Snowflake Schema Brands Products Channels Dates Sales Promotions © Minder Chen, 2004-2008 Customers Data Warehouse - 31 Hierarchy © Minder Chen, 2004-2008 Data Warehouse - 32 OLAP Solutions • • • • • Data Warehouse/Data Mart Dimensions Measures Cubes Europe Asia Cells © Minder Chen, 2004-2008 US Gadgets 130 135 140 142 Gizmos 205 390 350 475 Thingies 175 230 190 250 Widgets 310 340 410 450 Q1 Q2 Q3 Q4 Data Warehouse - 33 Operations in Multidimensional Data Model • Aggregation (roll-up) – dimension reduction: e.g., total sales by city – summarization over aggregate hierarchy: e.g., total sales by city and year total sales by region and by year • Selection (slice) defines a subcube – e.g., sales where city = Palo Alto and date = 1/15/96 • Navigation to detailed data (drill-down) – e.g., (sales - expense) by city, top 3% of cities by average income • Visualization Operations (e.g., Pivot) © Minder Chen, 2004-2008 Data Warehouse - 34 A Visual Operation: Pivot (Rotate) Juice 10 Cola 47 Milk 30 Cream 12 Product 3/1 3/2 3/3 3/4 Date © Minder Chen, 2004-2008 Data Warehouse - 35 Date Dimension of the Retail Sales Model © Minder Chen, 2004-2008 Data Warehouse - 36 Store Dimension • It is not uncommon to represent multiple hierarchies in a dimension table. Ideally, the attribute names and values should be unique across the multiple hierarchies. © Minder Chen, 2004-2008 Data Warehouse - 37 Multidimensional Query Techniques Why? What? Slicing Product Time Geography Why? Dicing Why? Drilling down © Minder Chen, 2004-2008 Data Warehouse - 38 ETL ETL = Extract, Transform, Load • Moving data from production systems to DW • Checking data integrity • Assigning surrogate key values • Collecting data from disparate systems • Reorganizing data © Minder Chen, 2004-2008 Data Warehouse - 39 Pivot Table in Excel © Minder Chen, 2004-2008 Data Warehouse - 40 Data Quality Issues • • • • • • • • • No common time basis Different calculation algorithms Different levels of extraction Different levels of granularity Different data field names Different data field meanings Missing information No data correction rules No drill-down capability © Minder Chen, 2004-2008 Data Warehouse - 41 Building The Warehouse Transforming Data © Minder Chen, 2004-2008 Data Warehouse - 42 The Anomalies Nightmare CUST # NAME ADDRESS 90328574 Digital Equipment 187 N. PARK St. Salem NH 01458 OEM 90328575 DEC 187 N. Pk. St. Salem NH 01458 OEM 90238475 Digital 187 N. Park St Salem NH 01458 $#% 90233479 Digital Corp 187 N. Park Ave. Salem NH 01458 Comp 90233489 Digital Consulting 15 Main Street Andover MA 02341 Consult 90234889 Digital Info Service PO Box 9 Boston MA 02210 Mail List 90345672 Digital Integration Park Blvd. Boston MA 04106 SYS INT No Unique Key Anomalies No Standardization TYPE Spelling Noise in Blank Fields How does one correctly identify and consolidate anomalies from millions of records? © Minder Chen, 2004-2008 Data Warehouse - 43 OLAP and Data Mining Address Different Types of Questions While reporting and OLAP are informative about past facts, only data mining can help you predict the future of your business. OLAP Data Mining What was the response rate to our mailing? What is the profile of people who are likely to respond to future mailings? How many units of our new product did we Which existing customers are likely to buy sell to our existing customers? our next new product? Who were my 10 best customers last year? Which 10 customers offer me the greatest profit potential? Which customers didn't renew their policies Which customers are likely to switch to the last month? competition in the next six months? Which customers defaulted on their loans? Is this customer likely to be a good credit risk? What were sales by region last quarter? What are expected sales by region next year? What percentage of the parts we produced yesterday are defective? What can I do to improve throughput and reduce scrap? Source: http://www.dmreview.com/editorial/dmreview/print_action.cfm?articleId=2367 © Minder Chen, 2004-2008 Data Warehouse - 44 Use of Data Mining • • • • • Customer profiling Market segmentation Buying pattern affinities Database marketing Credit scoring and risk analysis © Minder Chen, 2004-2008 Data Warehouse - 45 Associates Which items are purchased in a retail store at the same time? © Minder Chen, 2004-2008 Data Warehouse - 46 Sequential Patterns What is the likelihood that a customer will buy a product next month, if he buys a related item today? © Minder Chen, 2004-2008 Data Warehouse - 47 Classifications Determine customers’ buying patterns and then find other customers with similar attributes that may be targeted for a marketing campaign. © Minder Chen, 2004-2008 Data Warehouse - 48 Modeling Use factors, such as location, number of bedrooms, and square footage, to Determine the market value of a property © Minder Chen, 2004-2008 Data Warehouse - 49