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Table of Contents General Processing Steps Data Preprocessing Scaling of Data | |
See also: scales |
Range Scaling
Range scaling transforms the values to another range which usually includes
both a shift and a change of the scale (magnification, or reduction). The
data samples are transformed according to the following equation:
Mean Centering
Subtracting the mean of the data is often called "mean centering". It results in a shift of the data towards the mean. The mean of the transformed data thereafter equals zero:
Y = X - m
Standardization
Standardization (sometimes also called autoscaling) is the scaling procedure which results in a zero mean and unit variance of any descriptor variable. For every data value the mean m has to be subtracted, and the result has to be divided by the standard deviation s (note that the order of these two operations must not be reversed):
Y = ( X - m) / s
Last Update: 2005-Jul-16