First off, props to this krewe for tackling a large and scary topic, for exceptional clarity, and especially their humility. At about a 1% spread, the differences among languages are negligible.
Even a sample this size is too small:
A first glance at Figure 1(a) reveals that defect proneness of the languages indeed depends on the domain. For example, in the Middleware domain JavaScript is most defect prone (31.06% defect proneness). This was little surprising to us since JavaScript is typically not used for Middleware domain. On a closer look, we find that JavaScript has only one project, v8 (Google’s JavaScript virtual machine), in Middleware domain that is responsible for all the errors.
1% is not the "spread" (whatever that is), its the proportion of the variance in bug fixes that is attributable to languages. The other 99% is attributable to the number of commits (i.e. projects with more commits have more bugs. Well gee.)
Once you factor out the level of commit activity, language influence is actually quite large.
Even a sample this size is too small:
A first glance at Figure 1(a) reveals that defect proneness of the languages indeed depends on the domain. For example, in the Middleware domain JavaScript is most defect prone (31.06% defect proneness). This was little surprising to us since JavaScript is typically not used for Middleware domain. On a closer look, we find that JavaScript has only one project, v8 (Google’s JavaScript virtual machine), in Middleware domain that is responsible for all the errors.