Does the migration to GitHub relate to internal software quality?

Software development is more and more influenced by the usage of FLOSS (Free, Libre and Open Source Software) projects. These software projects are developed in web collaborative environments hosted on web platforms, called code forges. Many code forges exist, with different capabilities. GitHub is perhaps the largest code forge available, and many projects have been migrated from different code forges to GitHub. Given its success, we want to understand if its adoption has effect on the projects' internal quality. To consider objective measures of internal quality, we apply four known tools performing static analysis to extract metrics and code anomalies. These data is extracted on six versions of six FLOSS projects, and compared to understand if the migration to GitHub had any consistent effect over any of the considered measures.