A systematic difference or systematic error between an observed value
and some measure of the truth. Generally used to describe the inaccuracy
of a method relative to a comparative method in a method comparison
experiment. It also has a specific meaning in the statistical t-test,
where bias equals the difference between the mean values of the two
methods being compared or the average of all the differences between the
paired sample values.
The term "bias" was found in the following pages: