**Introduction**

Data mining integrates approaches and techniques from various disciplines such as machine learning, statistics, artificial intelligence, neural networks, database management, data warehousing, data visualization, spatial data analysis, probability graph theory etc. In short, data mining is a multi-disciplinary field.

## Statistics

Statistics includes a number of methods to analyze numerical data in large quantities. Different statistical tools used in data mining are regression analysis, cluster analysis, correlation analysis and Bayesian network. Statistical models are usually built from a training data set. Correlation analysis identifies the correlation of variables to each other. Bayesian network is a directed graph that represents casual relationship among data found out using the Bayesian probability theorem. Given below is a simple Bayesian network where the nodes represent variables whereas edges represent the relationship between the nodes.

## Machine Learning

Machine learning is the collection of methods, principles and algorithms that enables learning and prediction on the basis of past data. Machine learning is used to build new models and to search for a best model matching the test data. Machine learning methods normally use heuristics while searching for the model. Data mining uses a number of machine learning methods including inductive concept learning, conceptual clustering and decision tree induction. A decision tree is a classification tree that decides the class of an object by following the path from the root to a leaf node. Given below is a simple decision tree that is used for weather forecasting.

## Database Oriented Techniques

Advancements in database and data warehouse implementation helps data mining in a number of ways. Database oriented techniques are used mainly to develop characteristics of the available data. Iterative database scanning for frequent item sets, attribute focusing, and attribute oriented induction are some of the database oriented techniques widely used in data mining. The iterative database scanning searches for frequent item sets in a database. Attribute oriented induction generalizes low level data into high level concepts using conceptual hierarchies.

### Neural Networks

A neural network is a set of connected nodes called neurons. A neuron is a computing device that computes some requirement of its inputs and the inputs can even be the outputs of other neurons. A neural network can be trained to find the relationship between input attributes and output attribute by adjusting the connections and the parameters of the nodes.

### Data Visualization

The information extracted from large volumes of data should be presented well to the end user and data visualization techniques make this possible. Data is transformed into different visual objects such as dots, lines, shapes etc and displayed in a two or three dimensional space. Data visualization is an effective way to identify trends, patterns, correlations and outliers from large amounts of data.

## Summary

Data mining combines different techniques from various disciplines such as machine learning, statistics, database management, data visualization etc. These methods can be combined to deal with complex problems or to get alternative solutions. Normally data mining system employs one or more techniques to handle different kinds of data, different data mining tasks, different application areas and different data requirements.