I always wondered: is there actual study about this?
There is people arguing both ways with relatively good arguments, but what about quantifiable realities? As the author of GPL-licensed softwares, I didn't have much reasons to go that way or another, apart from hunch. Can we quantify those effects, so that we can properly align our licenses with the effect we want?
I’m not sure if there are studies, though it is probably something you could do. Maybe look at GPL vs MIT licensed software and see how each grows over time in terms of commits, lines of code, number of committers, number of issues, average time to close issues, total monthly downloads, etc. Of course metrics like these are pretty general, but at a large enough sample size I imagine there could be some observable patterns.
Of course, not everything is an optimization problem. So even if the metrics are better for x or y in general, people have their own reasons and beliefs about the world that might make one or the other better. I have generally felt that unless restrictiveness is important to you, minimally restrictive licensing is a good default choice.
There is people arguing both ways with relatively good arguments, but what about quantifiable realities? As the author of GPL-licensed softwares, I didn't have much reasons to go that way or another, apart from hunch. Can we quantify those effects, so that we can properly align our licenses with the effect we want?