<p>Unit testing sounds great to me, but I'm not sure I should spend any time really learning it unless I can convince others that is has significant value.  I have to convince the other programmers and, more importantly, the bean-counters in management, that all the extra time spent learning the testing framework, writing tests, keeping them updated, etc.. will pay for itself, and then some.</p>

<p>What proof is there?  Has anyone actually developed the same software with two separate teams, one using unit testing and the other not, and compared the results?  I doubt it.  Am I just supposed to justify it with, "Look it up on the Internet, everybody's talking about it, so it must be the right thing to do"?</p>

<p>Where is the hard evidence that will convince the laymen that unit testing is worth the effort?</p>

There are statistics that prove that fixing a bug found in the unit/integration test costs many times less than fixing once it's on the live system (they are based on monitoring thousand of real life projects).
Edit
: for example, as pointed out, the book "
Code Complete
" reports on such studies (paragraph 20.3, "Relative Effectiveness of Quality Techniques"). But there is also private research in the consulting field that proves that as well.