http://msnbc.com/news/768401.asp
excerpt:
...because “code and fix” leads to such extensive, costly rounds of
testing, even successful projects can be wildly inefficient. Incredibly,
software projects often devote 80 percent of their budgets to repairing
flaws they themselves produced — a figure that does not include the even
more costly process of furnishing product support and developing patches for
problems found after release.
“System testing goes on for almost half the process,” Humphrey says.
And even when “they finally get it to work, there’s still no design.” In
consequence, the software can’t be updated or improved with any assurance
that the updates or improvements won’t introduce major faults. “That’s the
way software is designed and built everywhere — it’s that way in spaceships,
for God’s sake.”