https://www.amazon.fr/Economics-Software-Quality-Capers-Jone...
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Capers Jones’ work does not “disprove” the triangle, and doesn’t even mention it. If anything, he implies that quality is a more complicated subject than the simple triangle implies, in that lower quality will have non-linear negative impacts on the project cost, time, and scope.
This is the triangle: https://en.m.wikipedia.org/wiki/Project_management_triangle
The original triangle assumes that as a PM, if you don’t recognize the trade off among scope, time, and cost, quality will suffer. This is true even with Jones’ data, but it is trite. The practices that help to ensure quality that are outside the triangle’s intent as a guideline: it is necessary to recognize these trade offs, but not sufficient, to ensure on-time, on-budget, sufficient quality and scoped delivery. One could manage tradeoffs among the time/cost/scope variables and still screw up their product’s quality due to poor methods and practices. Which is obvious, when you think about it.
Jones’ book also has a number of flaws - it’s hard to put his recommendations in practice (its more a survey than a “how to”), and he lacks data on a number of effective , newer practices that involve both quality, improved velocity, and requirements gathering or product/market fit. The result is that he tends towards promoting older practices that help quality but don’t have much impact on whether you’re building the right thing in the first place. To be fair, he admits this throughout the book, but being a data guy, shrugs and moves on to discuss what works with the data he has. A classic case of “looking for your car keys under the street lamp”. Nevertheless, it illustrates why quality pays for itself, which makes it important.
Many people have in mind this version of the "quality triangle" which we were discussing (not a Project Management triangle which I agree is more on point).
You get that a lot if search for "quality triangle": https://www.google.fr/search?tbm=isch&q=quality+triangle
Why is it commonly assumed that quality and cost and time are opposed to each other?
The Capers Jones books have one idea throughout, that is backed by data: for Software, quality is positively correlated with reduced time-to-market, low defects, and reduced costs.
> The practices that help to ensure quality that are outside the triangle’s intent as a guideline
There is a chapter about that in EoSQ, where each and every practice are measured and classified by efficiency, like TDD and code reviews. It's very interesting.
> The result is that he tends towards promoting older practices that help quality but don’t have much impact on whether you’re building the right thing in the first place.
Yes. I find he puts way too much faith in "off the shelf" software as the last bullet we may have.
tl;dr Capers Jones disprove the "quality triangle" big time, which is a product of intuitive reasoning without any basis, which doesn't apply to software. Just look at Intel at this very moment.
