The null hypothesis has to be that both approaches are equally effective. There simply isn't any evidence to suggest otherwise. At this point, it's premature t

The null hypothesis has to be that both approaches are equally effective. There simply isn't any evidence to suggest otherwise. At this point, it's premature to discuss whether static typing or dynamic typing affords benefits. The first step would be to look at a large set of real world open source projects written in different languages. If we see empirical evidence that projects written in certain types of languages consistently perform better in a particular area, such as reduction in defects, we can make a hypothesis as to why that is. For example, if there was statistical evidence to indicate that using Haskell reduces defects, a hypothesis could be made that the the Haskell type system plays a role here. That hypothesis could then be further tested, and that would tell us whether it's correct or not. I agree that these studies are hard to do, and that they'll always be imperfect. However, that's still the best tool we have for approaching this empirically.