How the trustworthiness of OSS products and artifacts can be assessed and predicted

for dissemination) The quality of Open Source Software (OSS) is much debated, since OSS is used by a continuously growing number of people and organizations. However, the discussions on the quality of OSS are usually based on opinions, feelings, personal preferences, and sometimes even political ideas. This document reports on an analysis of the perceived quality of OSS and the objectively measurable factors that may influence it. Specifically, the users’ and developers’ evaluations of the trustworthiness of OSS products (and of related qualities, like reliability and functionality) were collected and correlated to objective code measures. The result is a set of quantitative models that account for the dependence of the perceivable qualities of OSS on objectively observable qualities of the code. The ensemble of these models is called MOSST (Model of Open Source Software Trustworthiness). MOSST can be used by: 1) end-users and developers that would like to reuse existing OSS products and components, to evaluate the level of trustworthiness, reliability, usability and several other qualities of these OSS products that can be expected based on objectively observable characteristics of OSS product and projects; 2) the developers of OSS products, who can set code quality targets based on the level of trustworthiness, reliability, usability and several other qualities they want to achieve.