An Introduction to Data Mining
Discovering hidden value in your data warehouse
Data mining, the extraction of hidden predictive information from large databases, is a powerful new technology with great potential to help companies focus on the most important information in their data warehouses. Data mining tools predict future trends and behaviors, allowing businesses to make proactive, knowledge-driven decisions. The automated, prospective analyses offered by data mining move beyond the analyses of past events provided by retrospective tools typical of decision support systems. Data mining tools can answer business questions that traditionally were too time consuming to resolve. They scour databases for hidden patterns, finding predictive information that experts may miss because it lies outside their expectations.
Most companies already collect and refine massive quantities of data. Data mining techniques can be implemented rapidly on existing software and hardware platforms to enhance the value of existing information resources, and can be integrated with new products and systems as they are brought on-line. When implemented on high performance client/server or parallel processing computers, data mining tools can analyze massive databases to deliver answers to questions such as, "Which clients are most likely to respond to my next promotional mailing, and why?"
This white paper provides an introduction to the basic technologies of data mining. Examples of profitable applications illustrate its relevance to todays business environment as well as a basic description of how data warehouse architectures can evolve to deliver the value of data mining to end users.
The Foundations of Data Mining
Data mining techniques are the result of a long process of research and product development. This evolution began when business data was first stored on computers, continued with improvements in data access, and more recently, generated technologies that allow users to navigate through their data in real time. Data mining takes this evolutionary process beyond retrospective data access and navigation to prospective and proactive information delivery. Data mining is ready for application in the business community because it is supported by three technologies that are now sufficiently mature:
Commercial databases are growing at unprecedented rates. A recent META Group survey of data warehouse projects found that 19% of respondents are beyond the 50 gigabyte level, while 59% expect to be there by second quarter of 1996.1 In some industries, such as retail, these numbers can be much larger. The accompanying need for improved computational engines can now be met in a cost-effective manner with parallel multiprocessor computer technology. Data mining algorithms embody techniques that have existed for at least 10 years, but have only recently been implemented as mature, reliable, understandable tools that consistently outperform older statistical methods.
In the evolution from business data to business information, each new step has built upon the previous one. For example, dynamic data access is critical for drill-through in data navigation applications, and the ability to store large databases is critical to data mining. From the users point of view, the four steps listed in Table 1 were revolutionary because they allowed new business questions to be answered accurately and quickly.
|Evolutionary Step||Business Question||Enabling Technologies||Product Providers||Characteristics|
|"What was my total revenue in the last five years?"||Computers, tapes, disks||IBM, CDC||Retrospective, static data delivery|
|"What were unit sales in New England last March?"||Relational databases (RDBMS), Structured Query Language (SQL), ODBC||Oracle, Sybase, Informix, IBM, Microsoft||Retrospective, dynamic data delivery at record level|
|Data Warehousing &
|"What were unit sales in New England last March? Drill down to Boston."||On-line analytic processing (OLAP), multidimensional databases, data warehouses||Pilot, Comshare, Arbor, Cognos, Microstrategy||Retrospective, dynamic data delivery at multiple levels|
|"Whats likely to happen to Boston unit sales next month? Why?"||Advanced algorithms, multiprocessor computers, massive databases||Pilot, Lockheed, IBM, SGI, numerous startups (nascent industry)||Prospective, proactive information delivery|
Table 1. Steps in the Evolution of Data Mining.
The core components of data mining technology have been under development for decades, in research areas such as statistics, artificial intelligence, and machine learning. Today, the maturity of these techniques, coupled with high-performance relational database engines and broad data integration efforts, make these technologies practical for current data warehouse environments.
The Scope of Data Mining
Data mining derives its name from the similarities between searching for valuable business information in a large database for example, finding linked products in gigabytes of store scanner data and mining a mountain for a vein of valuable ore. Both processes require either sifting through an immense amount of material, or intelligently probing it to find exactly where the value resides. Given databases of sufficient size and quality, data mining technology can generate new business opportunities by providing these capabilities:
Data mining techniques can yield the benefits of automation on existing software and hardware platforms, and can be implemented on new systems as existing platforms are upgraded and new products developed. When data mining tools are implemented on high performance parallel processing systems, they can analyze massive databases in minutes. Faster processing means that users can automatically experiment with more models to understand complex data. High speed makes it practical for users to analyze huge quantities of data. Larger databases, in turn, yield improved predictions.
Databases can be larger in both depth and breadth:
A recent Gartner Group Advanced Technology Research Note listed data mining and artificial intelligence at the top of the five key technology areas that "will clearly have a major impact across a wide range of industries within the next 3 to 5 years."2 Gartner also listed parallel architectures and data mining as two of the top 10 new technologies in which companies will invest during the next 5 years. According to a recent Gartner HPC Research Note, "With the rapid advance in data capture, transmission and storage, large-systems users will increasingly need to implement new and innovative ways to mine the after-market value of their vast stores of detail data, employing MPP [massively parallel processing] systems to create new sources of business advantage (0.9 probability)."3
The most commonly used techniques in data mining are:
Many of these technologies have been in use for more than a decade in specialized analysis tools that work with relatively small volumes of data. These capabilities are now evolving to integrate directly with industry-standard data warehouse and OLAP platforms. The appendix to this white paper provides a glossary of data mining terms.
How Data Mining Works
How exactly is data mining able to tell you important things that you didn't know or what is going to happen next? The technique that is used to perform these feats in data mining is called modeling. Modeling is simply the act of building a model in one situation where you know the answer and then applying it to another situation that you don't. For instance, if you were looking for a sunken Spanish galleon on the high seas the first thing you might do is to research the times when Spanish treasure had been found by others in the past. You might note that these ships often tend to be found off the coast of Bermuda and that there are certain characteristics to the ocean currents, and certain routes that have likely been taken by the ships captains in that era. You note these similarities and build a model that includes the characteristics that are common to the locations of these sunken treasures. With these models in hand you sail off looking for treasure where your model indicates it most likely might be given a similar situation in the past. Hopefully, if you've got a good model, you find your treasure.
This act of model building is thus something that people have been doing for a long time, certainly before the advent of computers or data mining technology. What happens on computers, however, is not much different than the way people build models. Computers are loaded up with lots of information about a variety of situations where an answer is known and then the data mining software on the computer must run through that data and distill the characteristics of the data that should go into the model. Once the model is built it can then be used in similar situations where you don't know the answer. For example, say that you are the director of marketing for a telecommunications company and you'd like to acquire some new long distance phone customers. You could just randomly go out and mail coupons to the general population - just as you could randomly sail the seas looking for sunken treasure. In neither case would you achieve the results you desired and of course you have the opportunity to do much better than random - you could use your business experience stored in your database to build a model.
As the marketing director you have access to a lot of information about all of your customers: their age, sex, credit history and long distance calling usage. The good news is that you also have a lot of information about your prospective customers: their age, sex, credit history etc. Your problem is that you don't know the long distance calling usage of these prospects (since they are most likely now customers of your competition). You'd like to concentrate on those prospects who have large amounts of long distance usage. You can accomplish this by building a model. Table 2 illustrates the data used for building a model for new customer prospecting in a data warehouse.
|General information (e.g. demographic data)||Known||Known|
|Proprietary information (e.g. customer transactions)||Known||Target|
Table 2 - Data Mining for Prospecting
The goal in prospecting is to make some calculated guesses about the information in the lower right hand quadrant based on the model that we build going from Customer General Information to Customer Proprietary Information. For instance, a simple model for a telecommunications company might be:
98% of my customers who make more than $60,000/year spend more than $80/month on long distance
This model could then be applied to the prospect data to try to tell something about the proprietary information that this telecommunications company does not currently have access to. With this model in hand new customers can be selectively targeted.
Test marketing is an excellent source of data for this kind of modeling. Mining the results of a test market representing a broad but relatively small sample of prospects can provide a foundation for identifying good prospects in the overall market. Table 3 shows another common scenario for building models: predict what is going to happen in the future.
|Static information and current plans (e.g. demographic data, marketing plans)||Known||Known||Known|
|Dynamic information (e.g. customer transactions)||Known||Known||Target|
Table 3 - Data Mining for Predictions
If someone told you that he had a model that could predict customer usage how would you know if he really had a good model? The first thing you might try would be to ask him to apply his model to your customer base - where you already knew the answer. With data mining, the best way to accomplish this is by setting aside some of your data in a vault to isolate it from the mining process. Once the mining is complete, the results can be tested against the data held in the vault to confirm the models validity. If the model works, its observations should hold for the vaulted data.
An Architecture for Data Mining
To best apply these advanced techniques, they must be fully integrated with a data
warehouse as well as flexible interactive business analysis tools. Many data mining tools
currently operate outside of the warehouse, requiring extra steps for extracting,
importing, and analyzing the data. Furthermore, when new insights require operational
implementation, integration with the warehouse simplifies the application of results from
data mining. The resulting analytic data warehouse can be applied to improve business
processes throughout the organization, in areas such as promotional campaign management,
fraud detection, new product rollout, and so on. Figure 1 illustrates an architecture for
advanced analysis in a large data warehouse.
Figure 1 - Integrated Data Mining Architecture
The ideal starting point is a data warehouse containing a combination of internal data tracking all customer contact coupled with external market data about competitor activity. Background information on potential customers also provides an excellent basis for prospecting. This warehouse can be implemented in a variety of relational database systems: Sybase, Oracle, Redbrick, and so on, and should be optimized for flexible and fast data access.
An OLAP (On-Line Analytical Processing) server enables a more sophisticated end-user business model to be applied when navigating the data warehouse. The multidimensional structures allow the user to analyze the data as they want to view their business summarizing by product line, region, and other key perspectives of their business. The Data Mining Server must be integrated with the data warehouse and the OLAP server to embed ROI-focused business analysis directly into this infrastructure. An advanced, process-centric metadata template defines the data mining objectives for specific business issues like campaign management, prospecting, and promotion optimization. Integration with the data warehouse enables operational decisions to be directly implemented and tracked. As the warehouse grows with new decisions and results, the organization can continually mine the best practices and apply them to future decisions.
This design represents a fundamental shift from conventional decision support systems. Rather than simply delivering data to the end user through query and reporting software, the Advanced Analysis Server applies users business models directly to the warehouse and returns a proactive analysis of the most relevant information. These results enhance the metadata in the OLAP Server by providing a dynamic metadata layer that represents a distilled view of the data. Reporting, visualization, and other analysis tools can then be applied to plan future actions and confirm the impact of those plans.
A wide range of companies have deployed successful applications of data mining. While early adopters of this technology have tended to be in information-intensive industries such as financial services and direct mail marketing, the technology is applicable to any company looking to leverage a large data warehouse to better manage their customer relationships. Two critical factors for success with data mining are: a large, well-integrated data warehouse and a well-defined understanding of the business process within which data mining is to be applied (such as customer prospecting, retention, campaign management, and so on).
Some successful application areas include:
Each of these examples have a clear common ground. They leverage the knowledge about customers implicit in a data warehouse to reduce costs and improve the value of customer relationships. These organizations can now focus their efforts on the most important (profitable) customers and prospects, and design targeted marketing strategies to best reach them.
Comprehensive data warehouses that integrate operational data with customer, supplier, and market information have resulted in an explosion of information. Competition requires timely and sophisticated analysis on an integrated view of the data. However, there is a growing gap between more powerful storage and retrieval systems and the users ability to effectively analyze and act on the information they contain. Both relational and OLAP technologies have tremendous capabilities for navigating massive data warehouses, but brute force navigation of data is not enough. A new technological leap is needed to structure and prioritize information for specific end-user problems. The data mining tools can make this leap. Quantifiable business benefits have been proven through the integration of data mining with current information systems, and new products are on the horizon that will bring this integration to an even wider audience of users.
1 META Group Application Development Strategies: "Data Mining for Data Warehouses: Uncovering Hidden Patterns.", 7/13/95 .
2 Gartner Group Advanced Technologies and Applications Research Note, 2/1/95.
3 Gartner Group High Performance Computing Research Note, 1/31/95.
Glossary of Data Mining Terms
|analytical model||A structure and process for analyzing a dataset. For example, a decision tree is a model for the classification of a dataset.|
|anomalous data||Data that result from errors (for example, data entry keying errors) or that represent unusual events. Anomalous data should be examined carefully because it may carry important information.|
|artificial neural networks||Non-linear predictive models that learn through training and resemble biological neural networks in structure.|
|CART||Classification and Regression Trees. A decision tree technique used for classification of a dataset. Provides a set of rules that you can apply to a new (unclassified) dataset to predict which records will have a given outcome. Segments a dataset by creating 2-way splits. Requires less data preparation than CHAID.|
|CHAID||Chi Square Automatic Interaction Detection. A decision tree technique used for classification of a dataset. Provides a set of rules that you can apply to a new (unclassified) dataset to predict which records will have a given outcome. Segments a dataset by using chi square tests to create multi-way splits. Preceded, and requires more data preparation than, CART.|
|classification||The process of dividing a dataset into mutually exclusive groups such that the members of each group are as "close" as possible to one another, and different groups are as "far" as possible from one another, where distance is measured with respect to specific variable(s) you are trying to predict. For example, a typical classification problem is to divide a database of companies into groups that are as homogeneous as possible with respect to a creditworthiness variable with values "Good" and "Bad."|
|clustering||The process of dividing a dataset into mutually exclusive groups such that the members of each group are as "close" as possible to one another, and different groups are as "far" as possible from one another, where distance is measured with respect to all available variables.|
|data cleansing||The process of ensuring that all values in a dataset are consistent and correctly recorded.|
|data mining||The extraction of hidden predictive information from large databases.|
|data navigation||The process of viewing different dimensions, slices, and levels of detail of a multidimensional database. See OLAP.|
|data visualization||The visual interpretation of complex relationships in multidimensional data.|
|data warehouse||A system for storing and delivering massive quantities of data.|
|decision tree||A tree-shaped structure that represents a set of decisions. These decisions generate rules for the classification of a dataset. See CART and CHAID.|
|dimension||In a flat or relational database, each field in a record represents a dimension. In a multidimensional database, a dimension is a set of similar entities; for example, a multidimensional sales database might include the dimensions Product, Time, and City.|
|exploratory data analysis||The use of graphical and descriptive statistical techniques to learn about the structure of a dataset.|
|genetic algorithms||Optimization techniques that use processes such as genetic combination, mutation, and natural selection in a design based on the concepts of natural evolution.|
|linear model||An analytical model that assumes linear relationships in the coefficients of the variables being studied.|
|linear regression||A statistical technique used to find the best-fitting linear relationship between a target (dependent) variable and its predictors (independent variables).|
|logistic regression||A linear regression that predicts the proportions of a categorical target variable, such as type of customer, in a population.|
|multidimensional database||A database designed for on-line analytical processing. Structured as a multidimensional hypercube with one axis per dimension.|
|multiprocessor computer||A computer that includes multiple processors connected by a network. See parallel processing.|
|nearest neighbor||A technique that classifies each record in a dataset based on a combination of the classes of the k record(s) most similar to it in a historical dataset (where k ³ 1). Sometimes called a k-nearest neighbor technique.|
|non-linear model||An analytical model that does not assume linear relationships in the coefficients of the variables being studied.|
|OLAP||On-line analytical processing. Refers to array-oriented database applications that allow users to view, navigate through, manipulate, and analyze multidimensional databases.|
|outlier||A data item whose value falls outside the bounds enclosing most of the other corresponding values in the sample. May indicate anomalous data. Should be examined carefully; may carry important information.|
|parallel processing||The coordinated use of multiple processors to perform computational tasks. Parallel processing can occur on a multiprocessor computer or on a network of workstations or PCs.|
|predictive model||A structure and process for predicting the values of specified variables in a dataset.|
|prospective data analysis||Data analysis that predicts future trends, behaviors, or events based on historical data.|
|RAID||Redundant Array of Inexpensive Disks. A technology for the efficient parallel storage of data for high-performance computer systems.|
|retrospective data analysis||Data analysis that provides insights into trends, behaviors, or events that have already occurred.|
|rule induction||The extraction of useful if-then rules from data based on statistical significance.|
|SMP||Symmetric multiprocessor. A type of multiprocessor computer in which memory is shared among the processors.|
|terabyte||One trillion bytes.|
|time series analysis||The analysis of a sequence of measurements made at specified time intervals. Time is usually the dominating dimension of the data.|
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