Moinzadeh analyzes a variant of the classical (S-1,S) inventory model with Poisson demand. This variant differs from previously studied models in that an arriving demand facing stockout will backorder with probability αj if there are j backorders and is lost with probability 1-αj. For the case of constant resupply times Moinzadeh derives the steady state characteristics and, as these coincide with those in the case of exponential resupply times, conjectures that the results hold for arbitrary resupply times. This note uses the concept of quasi-reversibility developed by Kelly to prove this conjecture. That is, under general conditions the steady state probabilities of net inventory depend only on the mean of the resupply time distribution and are insensitive to its shape.
