Et (st) The mean, over training sets, of st. The subscript t in Et is redundant, since the only source of variability for st is the training sets, and it is included for emphasis. Vart (st) The variance, over training sets, of st ŝt An estimator of st. This estimator can be a function of only the training set t, i.e., ŝt = ŝt(t) (Chapters 2–5). It can also be a function of both the training and...