On continuous review stock control with multiple suppliers and non-negative lead times with special emphasis on Erlang distribution

This paper develops formulae for the moments of the effective lead time in the context of multi-sourcing when the individual lead times have non-negative support unlike the normal distribution. A formula for the distribution of effective lead time provides easy computational method for the mean and variance as well as any other moments. We provide exact formulae for the mean and variance of the effective lead time in the case of individual lead times having Erlang distribution. Computations are illustrated using a numerical example.