16 July 2014

Data Mining

Introduction: Knowledge Discovery and Data Mining (KDD) is an interdisciplinary area focusing upon methodologies for extracting useful knowledge from data. The ongoing rapid growth of online data due to the Internet and the widespread use of databases have created an immense need for KDD methodologies. The challenge of extracting knowledge from data draws upon research in statistics, databases, pattern recognition, machine learning, data visualization, optimization, and high-performance computing, to deliver advanced business intelligence and web discovery solutions [IBM Research].

"The basic task of KDD is to extract knowledge (or information) from lower level data (databases)." [1] Data, in its raw form, is simply a collection of elements, from which little knowledge can be gleaned. With the development of data discovery techniques the value of the data is significantly improved [UF].

A variety of methods are available to assist in extracting patterns that when interpreted provide valuable, possibly previously unknown, insight into the stored data. This information can be predictive or descriptive in nature. Data mining, the pattern extraction phase of KDD, can take on many forms, the choice dependent on the desired results. KDD is a multi-step process that facilitates the conversion of data to useful information.





Steps involved in the entire KDD process are [TechoPedia]:
  1. Identify the goal of the KDD process from the customer’s perspective. 
  2. Understand application domains involved and the knowledge that's required 
  3. Select a target data set or subset of data samples on which discovery is be performed.
  4. Cleanse and preprocess data by deciding strategies to handle missing fields and alter the data as per the requirements. 
  5. Simplify the data sets by removing unwanted variables. Then, analyze useful features that can be used to represent the data, depending on the goal or task. 
  6. Match KDD goals with data mining methods to suggest hidden patterns. 
  7. Choose data mining algorithms to discover hidden patterns. This process includes deciding which models and parameters might be appropriate for the overall KDD process. 
  8. Search for patterns of interest in a particular representational form, which include classification rules or trees, regression and clustering. 
  9. Interpret essential knowledge from the mined patterns. 
  10. Use the knowledge and incorporate it into another system for further action. 
  11. Document it and make reports for interested parties.

                             


                                              Fig: KDD process


Major KDD application areas include marketing, fraud detection, telecommunication and manufacturing.


Data Mining: Data mining (the analysis step of the "Knowledge Discovery in Databases" process, or KDD), an interdisciplinary subfield of computer science, is the computational process of discovering patterns in large data sets involving methods at the intersection of artificial intelligence, machine learning, statistics, and database systems.

In other words, data Mining is the automatic or semi-automatic analysis of large quantities of data to extract previously unknown interesting patterns such as groups of data records (cluster analysis), unusual records (anomaly detection) and dependencies (association rule mining). This usually involves using database techniques such as spatial indices. These patterns can then be seen as a kind of summary of the input data, and may be used in further analysis or, for example, in machine learning and predictive analytics. For example, the data mining step might identify multiple groups in the data, which can then be used to obtain more accurate prediction results by a decision support system. Neither the data collection, data preparation, nor result interpretation and reporting are part of the data mining step, but do belong to the overall KDD process as additional steps.


Text Mining: Text mining, also referred to as text data mining, roughly equivalent to text analytics, refers to the process of deriving high-quality information from text. High-quality information is typically derived through the devising of patterns and trends through means such as statistical pattern learning. Text mining usually involves the process of structuring the input text (usually parsing, along with the addition of some derived linguistic features and the removal of others, and subsequent insertion into a database), deriving patterns within the structured data, and finally evaluation and interpretation of the output. 'High quality' in text mining usually refers to some combination of relevance, novelty, and interestingness. Typical text mining tasks include text categorization, text clustering, concept/entity extraction, production of granular taxonomies, sentiment analysis, document summarization, and entity relation modeling (i.e., learning relations between named entities).

Text analysis involves information retrieval, lexical analysis to study word frequency distributions, pattern recognition, tagging/annotation, information extraction, data mining techniques including link and association analysis, visualization, and predictive analytics. The overarching goal is, essentially, to turn text into data for analysis, via application of natural language processing (NLP) and analytical methods.

A typical application is to scan a set of documents written in a natural language and either model the document set for predictive classification purposes or populate a database or search index with the information extracted.

Knowledge Discovery

  1. Supervised Learning
  2. Unsupervised Learning



Machine Learning: Machine learning, a branch of artificial intelligence, concerns the construction and study of systems that can learn from data. For example, a machine learning system could be trained on email messages to learn to distinguish between spam and non-spam messages. After learning, it can then be used to classify new email messages into spam and non-spam folders [WikiPedia].

The core of machine learning deals with representation and generalization.

Representation of data instances and functions evaluated on these instances are part of all machine learning systems. Generalization is the property that the system will perform well on unseen data instances; the conditions under which this can be guaranteed are a key object of study in the sub-field of computational learning theory.

There are a wide variety of machine learning tasks and successful applications. Optical character recognition, in which printed characters are recognized automatically based on previous examples, is a classic example of machine learning.

Information Retrieval:

Information Filtering

Knowledge Base: A knowledge base (KB) is a technology used to store complex structured and unstructured information used by a computer system. The term 'knowledge-base' was to distinguish from the more common widely used term database.

The original use of the term knowledge-base was to describe one of the two sub-systems of a knowledge-based system. A knowledge-based system consists of a knowledge-base that represents facts about the world and an inference engine that can reason about those facts and use rules and other forms of logic to deduce new facts or highlight inconsistencies.

The ideal representation for a knowledge-base is an object model (often called an ontology in AI literature) with classes, sub-classes, and instances.

Ontology: In computer science and information science, an ontology formally represents knowledge as a hierarchy of concepts within a domain, using a shared vocabulary to denote the types, properties and interrelationships of those concepts.


Ontologies are the structural frameworks for organizing information and are used in artificial intelligence, the Semantic Web, systems engineering, software engineering, biomedical informatics, library science, enterprise bookmarking, and information architecture as a form of knowledge representation about the world or some part of it.





References
[1] Fayyad, U.; Simoudis, E.; "Knowledge Discovery and Data Mining Tutorial MA1" from Fourteenth International Joint Conference on Artificial Intelligence (IJCAI-95) July 27, 1995 www-aig.jpl.nasa.gov/public/kdd95/tutorials/IJCAI95-tutorial.html