  Croston's method is generally viewed as superior to exponential smoothing
when demand is intermittent, but it has the drawbacks of bias and an inability
to deal with obsolescence, in which an item's demand ceases altogether. Several
variants have been reported, some of which are unbiased on certain types of
demand, but only one recent variant addresses the problem of obsolescence. We
describe a new hybrid of Croston's method and Bayesian inference called
Hyperbolic-Exponential Smoothing, which is unbiased on non-intermittent and
stochastic intermittent demand, decays hyperbolically when obsolescence occurs
and performs well in experiments.
