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Note: this content is reposted from my old Google Plus blog, which disappeared when Google took Plus down. It was originally published on 2016-05-18. My views and the way I express them may have evolved in the meantime. If you like this gist, though, take a look at Leprechauns of Software Engineering. (I have edited minor parts of this post for accuracy after having a few mistakes pointed out in the comments.)

Degrees of intellectual dishonesty

In the previous post, I said something along the lines of wanting to crawl into a hole when I encounter bullshit masquerading as empirical support for a claim, such as "defects cost more to fix the later you fix them".

It's a fair question to wonder why I should feel shame for my profession. It's a fair question who I feel ashamed for. So let's drill a little deeper, and dig into cases.

Before we do that, a disclaimer: I am not in the habit of judging people. In what follows, I only mean to condemn behaviours. Also, I gathered most of the examples by random selection from the larger results of a Google search. I'm not picking on anyone in particular.

The originator of this most recent Leprechaun is Roger S Pressman, author of the 1982 book "Software Engineering: a Practitioner's Approach", now in its 8th edition and being sold as "the world's leading textbook in software engineering".

Here is, in extenso, the relevant passage (I quote from the 5th edition, the first edition, which I do not have access to, reportedly stated "67 units" and that later became "between 60 and 100 units"; the rationale for this change is unclear.)

To illustrate the cost impact of early error detection, we consider a series of relative costs that are based on actual cost data collected for large software projects [IBM81]. Assume that an error uncovered during design will cost 1.0 monetary unit to correct. Relative to this cost, the same error uncovered just before testing commences will cost 6.5 units; during testing, 15 units; and after release, between 60 and 100 units.

This [IBM81] is expanded, in the References section of the book, into a citation: "Implementing Software Inspections", course notes, IBM Systems Sciences Institute, IBM Corporation, 1981.

Am I embarrassed for Pressman, that is, do I think he's being intellectually dishonest? Yes, but at worst mildly so.

It's bothersome that for the first edition Pressman had no better source to point to than "course notes" - that is, material presented in a commercial training course, and as such not part of the "constitutive forum" of the software engineering discipline.

We can't be very harsh on 1982-Pressman, as software engineering was back then a discipline in its infancy; but it becomes increasingly problematic as edition after edition of this "bible" lets the claim stand without increasing the quality of the backing.

Moving on, consider this 1995 article:

"Costs and benefits of early defect detection: experiences from developing client server and host applications", Van Megen et al.

This article doesn't refer to the cost increase factors. It says only this:

"To analyse the costs of early and late defect removal one has to consider the meaning and effect of late detection. IBM developed a defect amplification model (IBM, 1981)."

The citation is as follows:

"IBM (1981) Implementing Software Inspections, course notes (IBM Systems Sciences Institute, IBM Corporation) (summarised in Pressman 1992.)"

This is the exact same citation as Pressman's, with the added "back link" to the intermediate source. The "chain of data custody" is intact. I give Van Megen et al. a complete pass as far as their use of Pressman is concerned.

Let's look at a blog post by my colleague Johanna Rothman: http://www.jrothman.com/articles/2000/10/what-does-it-cost-you-to-fix-a-defect-and-why-should-you-care/

Johanna refers, quite honestly, to "hypothetical examples". This means "I made up this data", and she's being up front about it. She says:

"According to Pressman, the expected cost to fix defects increases during the product's lifecycle. [...] even though the cost ratios don't match the generally accepted ratios according to Pressman, one trend is clear: The later in the project you fix the defects, the more it costs to fix the defects."

I'm almost totally OK with that. It bothers me a bit that one would say "one trend is clear" about data that was just made up; we could have made the trend go the other way, too. But the article is fairly clear that we are looking at a hypothetical example based on data that only has a "theoretical" basis.

The citation:

Pressman, Roger S., Software Engineering, A Practitioner's Approach, 3rd Edition, McGraw Hill, New York, 1992. p.559.

This is fine. It's a complete citation with page number, still rather easy to check.

I am starting to feel queasy with this 2007 StickyMinds article by Joe Marasco:

https://www.stickyminds.com/article/what-cost-requirement-error

"The cost to fix a software defect varies according to how far along you are in the cycle, according to authors Roger S. Pressman and Robert B. Grady. These costs are presented in a relative manner, as shown in figure 1."

What Grady? Who's that? Exactly what work is being cited here? There's no way to tell, because no citation is given. Also, the data is presented as fact, and a chart, "Figure 1" is provided which was not present in the original.

This is shady. Not quite outright dishonest, but I'd be hard pressed to describe it more generously than as "inaccurate and misleading".

A different kind of shady is this paper by April Ritscher at Microsoft.

http://www.uploads.pnsqc.org/2010/papers/Ritscher_Incorporating_User_Scenarios_in_Test_Design.pdf

The problem here is a (relatively mild) case of plagiarism. The words "the cost to fix software defects varies according to how far along you are in the cycle" are lifted straight from the Marasco article, with the "according to" clause in a different order. But the article doesn't give Marasco credit for those words.

There's also the distinct possibility that Ritscher never actually read "Pressman and Grady". Do I have proof of that? No, but it is a theorem of sorts that you can figure out the lineage of texts by "commonality of error". If you copy an accurate citation without having read the original, nobody's the wiser. But why would you go to the trouble of reproducing the same mistake that some random person made if you had actually read the original source?

So we're entering the domain of intellectual laziness here. (Again, to stave off the Fundamental Attribution Error: I am not calling the person intellectually lazy; I am judging the behaviour. The most industrious among us get intellectually lazy on occasion, that's why the profession of tester exists.)

Next is this 2008 article by Mukesh Soni:

https://www.isixsigma.com/industries/software-it/defect-prevention-reducing-costs-and-enhancing-quality/

"The Systems Sciences Institute at IBM has reported that the cost to fix an error found after product release was four to five times as much as one uncovered during design, and up to 100 times more than one identified in the maintenance phase (Figure 1)."

We find the same level of deceit in a 2008 thesis, "A Model and Implementation of a Security Plug-in for the Software Life Cycle " by Shanai Ardi.

http://www.diva-portal.org/smash/get/diva2:17553/FULLTEXT01.pdf

"According to IBM Systems Science Institute, fixing software defects in the testing and maintenance phases of software development increases the cost by factors of 15 and 60, respectively, compared to the cost of fixing them during design phase [50]."

The citation is missing, but that's not really what's important here. We've crossed over into the land of bullshit. Both authors presumably found the claim in the same place everyone else found it: Pressman. (If you're tempted to argue "they might have found it somewhere else", you're forgetting my earlier point about "commonality of error". The only thing the "IBM Systems Science Institute" is known for is Pressman quoting them; it was a training outfit that stopped doing business under that name in the late 1970's.)

But instead of attributing the claim to "IBM, as summarized by Pressman", which is only drawing attention to the weakness of the chain of data custody in the first place, it sounds a lot more authoritative to delete the middle link.

I could go on and on, so instead I'll stop at one which I think takes the cake: "ZDLC for the Early Stages of the Software Development Life Cycle", 2014:

"In 2001, Boehm and Basili claimed that the cost of fixing a software defect in a production environment can be as high as 100 times the cost of fixing the same defect in the requirements phase. In 2009, researchers at the IBM Systems Science Institute state that the ratio is more likely to be 200 to 1 [7], as shown in Figure 2".

The entire sentence starting "In 2009" is a layer cake of fabrication upon mendacity upon affabulation, but it gets worse with the citation.

Citation [7] is this: "Reducing rework through effective requirements management", a 2009 white paper from IBM Rational.

Yes, at the century scale IBM Rational is a contemporary with the defunct IBM Systems Science Institute, but that's a little like attributing a Victor Hugo quote to Napoleon.

While Figure 2 comes straight out of the IBM paper, the reference to "IBM Systems Science Institute" comes out of thin air. And in any case the data does not come from "researchers at IBM", since the IBM paper attributes the data to Boehm and Papaccio's classic paper "Understanding and Controlling Software Costs", which was published not in 2009 but in 1988. (Both of them worked at Defense consultancy TRW.)

We've left mere "bullshit" some miles behind here. This isn't a blog post, this an official peer reviewed conference with proceedings published by the IEEE, and yet right on the first page we run into stuff that a competent reviewer would have red-flagged several times. (I'm glad I've let my IEEE membership lapse a while ago.)

Garden-variety plagiarism and bullshit (of which we are not in short supply) make me feel icky about being associated with "software engineering", but I want to distance myself from that last kind of stuff as strongly as I possibly can. I cannot be content to merely ignore academic software engineering, as most software developers do anyway; I believe I have an active duty to disavow it.

@Morendil
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Morendil commented Aug 3, 2021

Thanks for the perspective, Derek. "One size fits all" definitely leads to absurdities.

One of these for instance is this silly notion that there can be such a thing as the "industry average cost to fix one defect". And people can tell you with a straight face that this cost is $977.

I just found out to my dismay that in the 7th edition of his famous book, Pressman switched from citing the "Pressman ratios" (vaguely sourced to "course notes" from a 1981 IBM training program) to citing instead the "Wolverton ratios", and specifically the Cigital version of these numbers, where this $977 comes from.

Having previously tracked down these numbers, I know them to be in part ancient (prior to 1977), in part bogus (the $14,102 was made up by Cigital) and in any case misinterpreted (the Lewis study cited by Wolverton lumped together all changes and thus could not possibly have broken out the specific portion of the cost that went toward fixing defects).

Pressman's 7th edition came out in 2010. We can readily figure out what $977 in 1977 is worth in inflation-adjusted value in 2010; it's around $3265. We're only off by a factor of four.

My point here is that Pressman had thirty years to improve a book regarded as authoritative in the field of software engineering, and in these thirty years instead of coming up with better data he switched from one dubious source to a demonstrably worse one: older, less accurate, more distorted by intervening "telephone games".

The supposedly self-correcting nature of science is not on display here.

I don't quite share your implied optimism when you say "the way forward is to obtain data" - the data we collect is only as good as the underlying theoretical understanding that guides the manner of collecting it.

If we believe in an "industry average cost to correct one defect", then we will go on collecting aggregate measurements (e.g. "total cost of development"), dividing those into other aggregate measurements (say "total number of defects recorded"), pretending that this operation has any sort of meaning, and then compounding the error by averaging it over several organizations that work in entirely unlike ways, yielding an absolutely meaningless "industry average". All this data collection (which will probably have had real costs, in money but also in motivation of the poor programmers upon which management has imposed an empty and unnecessary ritual) will have not advanced our knowledge of "how to write software better" one iota.

The way forward, I suspect, is to clear the deck of some outdated notions and figure out what really matters - then we might have a chance of collecting data about that. We need to start searching for our keys where we dropped them, not under the lamppost that shines a convenient light.

The work you're doing serves an important purpose - it inventories the lampposts (those with public data sets, anyway), giving us an idea of where it's still dark. And perchance some of these lampposts will not be too far from dropped sets of keys. But I'm yearning for more.

Nature may abhor a vacuum, but as people we can build up a tolerance to saying "we just don't know". Unlike Nature we can muster the courage to scrap what has so far felt like an indispensable foundation, but might in fact be an anchor preventing us from making real progress. One thing I have in mind for instance is Hillel Wayne's contention that perhaps the least effort, highest impact on software development productivity would be to get more and better sleep. ESEUR stands out by devoting ample space to human cognition, but how many books on software engineering fail to even acknowledge that it's cognitive work done by humans ?

@Derek-Jones
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The only way to clear away false notions is to figure out what works, and to give people the evidence.

Perception is important. We need to brand research that does not involve significant amounts of real world data as vanity research.

I don't experience any difficulty in convincing people in industry that existing folklore is based on dodgy data (or none at all). But having made somebody receptive to an alternative theory/reality, I have nothing to give them. People are visibly let down, and don't like the idea of "the situation is unknown". Unless the vacuum can be filled, I don't think it is not a good use of my time talking people out of a folklore belief.

We are still a long way from using theory to guide the collection of data. Today's collection methodology is to ask people if they have data (most don't), and when some is found ask for a copy (I don't see things changing for many years). I seem to be the only person actively searching for data; from what I have seen, other researchers acquire industry data through one of their students having worked someplace, or having an existing relationship with an organization. Most are burrowing down the github rabbithole.

Software research is primarily done by people interested in software. I have had academics tell me of the perception difficulties they would face, should they get involved in 'human stuff'. I have also been told about the difficulties of getting human issue papers published. One solution is to start funding psychology and sociology researchers to investigate software issues (psychologists can be snobbish about applied research; they see their calling as understanding the operation of the human mind).

Where do people go to talk about evidence-based software engineering? We need a mailing list (please no walled garden such as Facebook). I would make a poor moderator, volunteer needed :-)

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