[yogthos]

I think it's a good starting point to look at a large number of open source projects in the wild. The individual differences in skill, size, etc. average out between them. It's important to establish whether any statistically significant trends exist before anything further can be discussed meaningfully.

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 then 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.

However, this is pretty much the opposite of what happens in discussions about features such as static typing. People state that static typing has benefits and then try to fit the evidence to fit that claim. Even the authors of this study fall into this trap. They read into the preconceived notions that are not supported by the data in their results. The differences they found are so small that it's reasonable to say that the impact of the language is negligible.

[runT1ME]

Yes, surely it's a coincidence that two of the most powerful statically typed languages have the least defects.

[yogthos]

Perhaps you should actually read the conclusion before getting too excited:

>One should take care not to overestimate the impact of language on defects. While the observed relationships are statistically significant, the effects are quite small. Analysis of deviance reveals that language accounts for less than 1% of the total explained deviance.

Nor do these most powerful statically typed languages appear to perform any better than dynamically typed Clojure and Erlang.