Analytics for the Internet of Things (IoT)

Centering and scaling

Measurement values can be from vastly different ranges. Barometric pressure is typically measured in millibars with an average sea level at 1013 mbar while atmospheric temperatures normally range from -30 to 40 celsius. A method to adjust for these differences is called centering. You can center a feature by calculating the average of all the values in the feature, and then subtract it from each individual value. The resulting transformed feature has a mean of zero.

Imaging drawing a right triangle where the first side is 100 m long, the second is 1 m, and the third is 100.03 m long. It would be barely distinguishable from a 100 m long line. Now, imagine that the first side grows to 10,000 m long with the second side ...