Let’s consider here a project with a significant problem we haven’t found. If the project’s product is to be a chair, maybe we have cut a leg too short. If the project’s product is software, maybe a function we designed with two parameters actually needs three (or reports answers in units different than a consuming function assumes it reports, maybe miles per hour instead of meters per second). This discussion is not about a misspelled word in a quick and informal email message, for example.
Do we get to choose between finding that problem or not? Well … (he he) … since our discussion is about significant problems, we’ll find it. And as one of the many corollaries to Murphy’s Law says, “If you have a problem, you’ll find that problem at the worst possible time.” (There’s something irresistibly pessimistic about that Law and all its Corollaries!)
You’ll find that problem just after you’ve spent lots of effort with the short chair leg in a lathe, getting sanded, and getting just the right finish (all of which was a waste of effort, of course, but you didn’t know that yet). It’ll happen just after you or your tester tell your executive that your code is 99 percent through testing, that the results look good, that you expect to complete ahead of schedule, and that the profits for this product are likely to start early. Or your customer will find the problem. (That would be embarrassing!) You’ll find that problem. It’ll hurt.
Let’s do something about it. And let’s focus now on creating software. Barry Boehm published once or twice (tongue-in-cheek) in a long and continuing software engineering career. In 1981, he wrote Software Engineering Economics, which contains the famous Constructive Cost Model (COCOMO) used for estimating the size and duration of software development efforts. It also contains (page 40) a graph showing the increasing cost to fix a problem introduced in requirements. The chart makes the point that if the problem costs roughly $15 to fix during requirements, it costs something like $50 in design, $100 during construction, $200 during development test, $500 during acceptance test, and $1,800 during operation. Many other sources of similar age make similar arguments and cite other cost studies. Their numbers vary, but let’s agree: cost to fix grows rapidly with time.
One message from those studies is: projects need a strong sense of urgency about finding problems we must fix because of the rapid increases in cost.
Another message is that a key question in managing a project is, “How much is the optimal spending now (in dollars, hours, process, whatever) to detect more problems earlier and get the greatest benefit from the current lower price of fixes?”
Sound good? Well … it certainly sounded good enough to form an orthodoxy in our professions. (Perhaps, anyway. It felt like that!)
From the current perspective, is there a problem?
Well … from today’s perspective, many of us would feel the data collection seems to presume use of the waterfall development model. Fewer projects use a waterfall model today.
And … many in our industry now have experience working projects without spending lots of time in review of past work. Many of us feel that the right answer to the question above is spending no time specifically looking for past problems.
And we achieve great results.
And our stakeholders love the new relationships with us as service providers.
(Well … not every time. New project models aren’t “the silver bullet”. And there are lots of other reasons projects don’t do as well as we want; many still need work.)
I refer, of course, to the development models advising us to strive for market agility (Scrum, Lean, Kanban, and Extreme Programming are commonly-cited examples). I intend to write more about these in future posts. For now, I’ll say: Much of the market has already moved one (or more) of these directions.
And what about the advice derived from the statistics Dr. Boehm cited? I’ll say projects need the same sense of urgency about finding errors; we’ll find problems differently than we most commonly thought about then. Projects using today’s agile models probably expect to discover those errors during their frequent interaction with customers (“early feedback”). And we expect to fix problems during the first iteration in which the customer wants us to fix them. And that advice sounds great … Why would anyone oppose?
And what about Dr. Boehm’s career after writing the book I mentioned? Well, in 1988, he published an often-cited description (info) of his “Spiral Model” of iterative software development. Both his works cited here influenced thought leaders who contributed to other models later collectively called “agile”. He is now an AIAA Fellow, an ACM Fellow, an IEEE Fellow, an INCOSE Fellow, and a member of the National Academy of Engineering.
He is one thought giant on whose shoulders we stand today. May we all learn …
//Later edit: Fixed a broken link.