There was another 1981 paper that went into this by Boehm "Software Engineering Economics", but I can't find the details right now. This NASA publication [1] c

There was another 1981 paper that went into this by Boehm "Software Engineering Economics", but I can't find the details right now. This NASA publication [1] cites a number of studies and the cost increase factors they estimate for various stages of development, including the Boehm study. [1]: https://ntrs.nasa.gov/api/citations/20100036670/downloads/20100036670.pdf https://ntrs.nasa.gov/api/citations/20100036670/downloads/20...