It's interesting and surprising to me that it's difficult to show TDD actually has a positive effect.

How does the non TDD method work? Test just after in short iterations probably works well too, but it appears the methodology commonly compared against doesn't actually involve any automated developer testing. I wish the alternative "conventional" methodology was defined better - what is it?

Is it devs testing by hand and throwing it over the wall and hoping for the best?

#programming 

 @5d859d2e testing it by running it and clicking around or whatever, then eventually encoding those behaviors as tests once they stabilize