[dragonwriter]

> The cost of fixing a bug isn't just the deployment effort. It's also the investigation, the impact analysis for any potential fix, and the mitigation of any unwanted side effects on other code that is related to wherever the bug is.

...and also the mitigation of the problems the bug has caused, e.g., to production data or business actions. This is a big driver of cost of bugs that get into production.

> I'm not sure what since-debunked bit of research you were referring to,

There was a popular 90s report that concluded a 10× cost for each step from requirements to design to testing to production; I suspect that’s the one.

[Silhouette]

There was a popular 90s report that concluded a 10× cost for each step from requirements to design to testing to production; I suspect that’s the one.

That rings a bell. Possibly it was something cited in the original Code Complete? Could also have been cited by one of the consultants pushing (at the time) relatively new and unusual testing and review practices as evidence for why their advice was worthwhile. But you're right, I think the exponential cost increase argument was based on a very waterfall-y development process.