Is agile scientifically proven

Question

Are there any scientific studies that have compared agile to other software development methodologies? I think agile is a nice way of working, but is there any scientific basis for it?

I'm looking for something like this, except this study only deals with TDD. Have there been studies about agile in general?

I'm asking this because I met a agile-zealot who claimed the agile way of working produces better software than all the other ways of working. He presented this as a fact, which I don't think it is.