I was very amused by Mark Debono’s diagram ‘A bug goes skateboarding on Boehm’s Curve’ posted on LinkedIn’s ‘EuroSTAR Software Testing Community’ group in May 2014. However I don’t agree with the statement “bugs are always more expensive to fix later on in the process” (my italics): www.linkedin.com/groups/bug-goes-skateboarding-on-Boehms.
For those of you who don’t belong to LinkedIn, or that particular community, my view is:
“Whilst I share your implied sentiment about investing early in software quality, I prefer the original ISEB/BCS Foundation Level syllabus positioning of this in respect of the economics of early testing: “the cost of testing is generally lower than the cost associated with major faults”.
Barry Boehm did conclude in Software Engineering Economics, 1981 (pp 39-41) that empirical data indicated errors were typically one hundred times more expensive to correct in maintenance for larger projects (excluding additional operational costs incurred by the error). However, he also concluded based on data for smaller projects (using approaches such as prototyping) that different cost-to-fix escalation curves indicated trade-off points where proceeding with a prototype could be more cost efficient than trying to pin down requirements in full detail.
In his more recent book Balancing Agility and Discipline, 2004, he continues to discuss cost-to-fix escalation in relative terms depending on the development approach rather than absolute terms (e.g. Appendix E1).”