The process of data mining is concerned with extracting patterns from the data by using techniques such as classification, regression, link analysis, segmentation or deviation detection. Classification involves mapping data into one of several predefined or newly discovered classes. Regression methods involve assigning data a continuous numerical variable based on statistical methods. One goal in using regression methods is to extrapolate trends from a few samples of the data. Link analysis involves evaluating apparent connections or links between data in the database. Deviation detection identifies data values that are outside of the norm, as defined by existing models or by evaluating the ordering of observations. Segmentation identifies classes or groups of data that behave similarly, according to an established metric. These methods of data mining are typically used in combination with each other, either in parallel or as part of a sequential operation.