This paper examines the performance of two different (s,Q), inventory models for spare parts in a production plant of confectionery in The Netherlands, a simple and an advanced model. The simple approach is more or less standard: undershoot of the reorder level is not taken into account, the...

Production Planning and Inventory Control (PPIC) is an essential dynamics of the logistical performance of manufacturing organizations. In this paper, we discuss the development of a PPIC system in a process industry. The process manufacturing industry has not embraced the new Advanced Planning...

To model demand, the normal distribution is by far the most popular; the disadvantage that it takes negative values is taken for granted. This paper proposes two modifications of the normal distribution, both taking non-negative values only. Safety factors and order-up-to-levels for the familiar...

For a number of statistical applications, experts' subjective estimates are needed for distributional parameters, like mean and variance; sometimes even the whole density is wanted. The literature agrees that it is wise behaviour to ask the expert only quantile estimates; from these, the desired...

In this paper we are especially interested how to optimize the production/inventory control for a manufacturer of sweets, under the following circumstances: short production lead times in combination with an intermittent demand pattern for the so-called B-taste items. As for A-taste items a...

The paper discusses the problem of a fallible auditor who assesses the values of sampled records, but may make mistakes. To detect these mistakes, a subsample of the checked elements is checked again, now by an infallible expert. We propose a model for this kind of double check, which takes into...

We consider multivariate regression where new dependent variables are consecutively added during the experiment (or in time). So, viewed at the end of the experiment, the number of observations decreases with each added variable. The explanatory variables are observed throughout. In a previous...

In this paper we present an approximation method to compute the reorder point s in a (R; s; Q) inventory model with a service level restriction, where demand is modeled as a compound Bernoulli process; that is, with a xed probability there is positive demand during a time unit, otherwise demand...

Inventory models need information about the demand distribution. In practice, this information is not known with certainty and has to be estimated with often relatively few historical demand observations. Using these estimates leads to underperformance. This paper focuses on gamma distributed...

The exact expressions for the convolutions of gamma distributions with different scale parameters is quite complicated. The approximation by means of another gamma distribution is shown to be remarkably accurate for wide ranges of the parameter values, especially if more than two random...