standard deviation

Terms from Artificial Intelligence: humans at the heart of algorithms

Page numbers are for draft copy at present; they will be replaced with correct numbers when final book is formatted. Chapter numbers are correct and will not change now.

The standard deviation (σ) is a measure of spread in \term{statistics}. It is caclualted by taking the square root of the \term{variance}, which is itself the average of the square of difference of values from their \term{arithmetic mean}. The standard deviation of a simple set of N numbers xi> with mean μ is:
      σ   =   √ ( Σ (xi>− μ)2  /  N )

Used in Chap. 7: pages 102, 103, 104; Chap. 8: page 117; Chap. 10: pages 148, 150; Chap. 12: page 183