Edited by

Some authors maintain that open source software processes areparticularly well-suited for delivering good reliability. We discuss thiskind of statement, first clarifying the different measures of reliabilityand of a process’s ability to deliver it that can be of interest, and thenproposing a way of addressing part of it via probabilistic modelling.We present a model of the reliability improvement process that resultsfrom the use of the software and the fixing of reported faults, whichtakes account of the effect on this process of the variety of software usepatterns within the user community. We show preliminary, interest-ing, non intuitive results concerning the conjecture that a more diversepopulation of users engaged in reporting faults may give OSS processesan advantage over conventional industrial processes, in terms of fastreliability growth after release, and discuss further possible develop-ments.