A note on variance reducing group maintenance policies

Group replacement policies for machines operating in parallel are generally evaluated by computing the associated expected cost per unit time. However, as with all stochastically evolving systems, variance should play an important managerial role. No matter which policy is used by the maintenance manager, knowledge of the associated variance provides important information about the variability of the costs that will be incurred by using this policy. Additionally, there will be cases where a decision maker is willing to incur increased expected cost per unit time in order to reduce the variability of the costs among cycles. This paper demonstrates that it is feasible and practicable to calculate the variance of the cost per unit time associated with group maintenance policies.