Is there hard evidence of the ROI of unit testing?

Question

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

Answer 1

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.