Showing posts with label requirements. Show all posts
Showing posts with label requirements. Show all posts

Sunday, November 19, 2017

Terchnical Reviews and Organizational Renewal

We know that success can breed failured and doesn't automatically renew itself. I would like to offer some ideas on how this self-defeating tendency can be resisted.

One way toward renewal is through new perspectives gained from outside technical audits, but audits suffer from several serious disabilities. For one thing, audits are done intermittently. In between one audit and the next, the programmers don't stop programming, the analysts don't.stop analyzing, and the operators don't stop operating. Sometimes, though, the managers stop managing, And there's the rub.

A comparable situation exists when a firm has a system of personnel reviews mandated, say, every six months for each employee. Under such a system, managers tend to postpone difficult interactions with an employee until the next appraisal is forced upon them. A huge dossier may be accumulated, but then ignored in favor of the last, most conspicuous blunder or triumph. Good managers realize that the scheduled personnel review is, at best, a backup device—to catch those situations in which day-to-day management is breaking down.

In the same way, the outside technical audit merely backs up the day-to-day technical renewal processes within the shop. It may prevent utter disasters, but it's much better if we can establish technical renewal on a more continuous and continuing basis. One way to do this is through a technical team, such as an Agile team. For now, though, I want to introduce, or reintroduce, the concept of formal and informal technical reviews as tools for renewing the technical organization.

The Agile Manifesto requires "technical excellence" and "simplicity," and states: 

At regular intervals, the team reflects on how to become more effective, then tunes and adjusts its behavior accordingly. 

To achieve these and other goals, Agile teams conduct "walkthroughs" and "inspections," but these are only two very specific examples of technical review procedures used by Agile teams. In my reading and consulting, I've uncovered dozens of major variants of these two types of review, plus literally hundreds of minor variants that shops have introduced to make the review more suitable to their environments, whether or not they claim to be "Agile."

A more general definition of a technical review could be 

1. a review of technical material on the basis of content (this is what makes it a "technical" review, rather than, say, a financial or personnel review)

2. which is done openly by at least two persons (this is what distinguishes it from "desk checking")

3. who take lull responsibility for the quality of the review (not, please note, for the quality of the product)

Then we distinguish between the informal and formal review. A formal review produces a written report to management. That report is the formal part.

Informal reviews (that is, reviews which need not terminate with a written report to management) are also excellent devices for an organization's self-renewal. Informal reviews take all forms of technical reviews, and are practiced everywhere almost all the time. Indeed, they are an essential part  of the real world of programming work.

For instance, a team member passes a diagram to a teammate for an opinion on how to represent a particular design. Someone asks help from someone else in finding an error. A set of test cases is passed around to see if anyone can think of something that's been overlooked. One person reads another's user document to see if it's understandable.

Without a constant flow of such informal reviewing of one another's work, programming any meaningful project would be impossible. Formal reviewing, on the other hand, is not essential to programming. Many small projects are accomplished without formal reviewing, which is why some programmers don't appreciate the need for formal reviewing. 

As projects grow 'larger and more complex—as they are inclined to do in successful shops—the work of many people must be coordinated over a long period of
time. Such coordination requires management—though not necessarily managers—and such management requires reliable information. Formal reviews, essentially, are designed to provide reliable information about technical matters—particularly to non-technical people.

Clearly, a successful system of formal technical reviews—that is, a system that provides management with reliable information on technical matters—is essential to management participation in the organizational-renewal process. For the large shop, formal reviews provide information that the small shop manager gets "through the seat of the pants." Many, many failures of previously successful programming organizations an be traced directly to the breakdown of the earlier informal mechanisms for communicating reliable information about technical matters.

There may, of course, be other ways of getting this kind of information, and many smaller shops do an excellent job without any system of formal reviews. Even those shops, however, may benefit from an explicit system of reviews to supplement their implicit, or informal, existing system. 

Principally, the formal technical review provides reliable self-monitoring. An informal system may work just as well as a formal one, and if so, there are many reasons to prefer to keep the reviewing informal. In any case, there will always be an informal system at least supplementing the formal one, but we should really view the formal system as supplementing the informal. Its formality guards against creeping deterioration of the organization.

Regular reviews of specifications, designs, code, test plans, documentation, training materials, and other technical matter have many beneficial "side effects" on the health and success of an installation. Reviews have a very marked effect on maintenance—that quicksand in which a thousand successful shops have met an untimely end. A typical program that has been thoroughly reviewed during its development will

1. require less maintenance work per change

2. require fewer changes caused by poor specification, design, coding, or testing.

Instituting a program of technical reviews will not, of course, have any immediate effect on the existing burden of maintenance carried like an albatross from a sinful programming past. Indeed, when maintenance programmers participate in reviews of newer code, they may be further discouraged by the poor quality of the code with which they are burdened. But, the situation can improve rather quickly, for a variety of reasons:

1. Some new ideas can be applied even to patches to old programs, though naturally limited by poor existing structure and style.

2. Through mutual participation in reviews, the entire shop quickly obtains a realistic and sympathetic picture of the true dimensions of the maintenance situation.

3. The worst maintenance problems will, through frequent reviews, become exposed to fresh air and sunlight.

Quite frequently, installation of a review system is quickly followed by replacement of the most cantankerous old beasts left over from the Stone Age of Programming. The effect of even one such replacement on maintenance morale is a wonder to behold,

Other activities besides maintenance are similarly affected. In the long run, certainly, reviews have a remarkable effect on staff competence, perhaps the most important element in continuing success. We also see increased morale and professional attitude, reduced turnover, more reliable estimating and scheduling, and better appreciation of the management role in project success. (Usually, the technical staff has had no difficulty in appreciating the management role in project failure.)

At the same time, reviews provide management with a better appreciation for staff competence, both individually and collectively. The unsung hero who quietly saved a dozen shaky projects is now sung far and wide. The "genius programmer" who was always the darling of the executives has been exposed for the empty and obsolete shell the technical staff always knew, but couldn't expose to management.

No other factor is more depressing to a technical organization than misappraisal of technical competence by non-technical management. The openness of technical reviews marks an end to that misappraisal era. No longer will we all feel cheated by charlatans and incompetents.

As a consultant, I visited dozens of installations every year. The best way to summarize the effects of properly instituted reviews is to report that after five minutes in an installation, I can tell—without asking directly—to what extent there is an effective review-practice, formal or informal.

How do I tell? Metaphorically, I tell in the same way a government health inspector tells about a food processing plant—by the way it smells. It's hard to describe, but when you smell the difference, you-know it!

* * * * * *

Looking back over this essay, I sense its inadequacy to the task at hand. Those programmers and analysts who have experienced a shop with a properly functioning system of reviews will know all this without my giving any details. They've experienced it, and if they are professionals, they'll never agree to work in any other kind of environment.

But those who have never experienced such an environment of a self-renewing organization will not understand, or will misunderstand, what I've written. Some of them will have experienced a misguided attempt to institute reviews. Perhaps the attempt was in the form of a punitive management mandate. Perhaps it was merely a case of another programmer who read one article and blundered ahead with 99% enthusiasm and 1% information—and zero human feeling. To these people, the experience of "reviews" will have left a bitter taste, or a painful memory. They will not recognize their experience in what I've written.

In many ways, technical reviewing is like bicycling. Up until the time you first discover your balance in one miraculous instant, the whole idea seems impossible, contrary to nature, and a good way to break a leg. Indeed, if you'd never seen a cyclist before, and had the process described to you, you'd most certainly declare the whole procedure impossible. And, without instruction and encouragement from experienced cyclists, along with reliable "equipment," the most likely outcome would certainly be skinned knees, torn pants, and a few lumps on the head. And so it has been with technical reviews—until now—-so don't go off and try to learn the whole process on your own.

If you want to get started renewing the success of your own shop through a system of technical reviews, find an experienced shop, or a person from an experienced shop, to guide you. Listen to them, Read the literature. Then try a few simple reviews on an experimental basis, without much fanfare.

Adapt the "rules" to your own environment. Be forgiving and humane. Your rewards  will not be long in coming.


references: 




Wednesday, November 15, 2017

What's it like to rewrite a program from scratch?

This is an interesting question because so many programmers are so afraid of this task that they would never even ask it. Is this reluctance agile, or Agile?

But why would you want to do rewrite a program from scratch? The most important reason is to increase maintainability. In the initial writing, the focus is generally on merely getting the job done, without thinking of the program's future. Over their lifetime, many programs cost far more to maintain than to write originally, especially when the original program has become a thing of rags and patches.

A second, and often secondary reason to rewrite a program is efficiency. Newly constructed programs and highly patched old programs sometimes turn out to be slower than desired, but such inefficiency cannot erased by any amount of tweaking. Instead, increased efficiency requires a new approach, an approach that needs to be implemented from scratch.

But isn't rewriting expensive? Not usually. In fact, it’s generally far, far easier to rewrite a program from scratch than to write some brand-new program.

Why would a fresh start-over be cheaper than the original? Because in writing the original program, the original programmers answered so many difficult questions about what was really wanted. Requirements haven't changed, and most of the thought put into testing can be reused.

Those questions—requirements and test—usually make up more than half the total work put into a program. They have already been answered—but only if you resist the temptation to change those answers. If you don’t resist, then rewriting the program can be arbitrarily difficult.

I wish more programmers had to courage to rewrite some clumsy programs from scratch, rather than patch and patch and patch. And I wish their managers would encourage sensible rewriting, rather than force programmers to waste their skills, time, and energy keeping ancient programs on life support.


Monday, October 31, 2016

What's the most complex thing about software development?

What's the most complex thing about software development?

Interesting question.

So far, on Quora.com, there have been four excellent answers to this question: discussing 
- the confusing role of people, 
-the requirements problems,
-the interactions with the physical world.

Each of these factors certainly makes software development more complex, and processes such as Agile are designed to cope with this complexity. But, the ultimate complexity factor is software testing.

Why testing? In the software development literature, testing is not usually treated as a glamorous part of development, but when we're testing, we're up against the Second Law of Thermodynamics, which warns us that perfection is ultimately unobtainable.

So, even if we absolutely knew all the requirements (which we can't, of course), kept all the human factors under control (also impossible), and knew exactly all the physical properties of the real world (once more, impossible), we would still never be able to perform the infinite number of tests to cover all possible situations.

In other words, the software could still surprise us at any time. That's what I call complexity.

Of course, we can still work hard to solve these other problems. On requirements, for instance, see our Exploring Requirements books.





But no matter how hard you try, you'll still be faced with the testing problem. To understand this problem and what you can do to reduce (but not eliminate) it, take a look at Perfect Software and Other Illusions about Testing.

Wednesday, August 17, 2016

How does a tester help with requirement gathering?



The question was posed: "How does a tester help with requirement gathering?" A number of good, but conventional, answers were given, so I decided to take my answer to a meta-level, like "what is the tester's job, generally, and how does that relate to this question?"
The tester’s job is to test, that is, to provide information about the state of a system being built or repaired. Therefore, the tester should help with requirement gathering or any other phase of development where the job of testing might be affected.
A professional tester will involve her/himself in all phases, not such much to “help” others do their job, but to assure that s/he will be able to do a professional job of testing. So, for example, in the requirements work, the tester should obviously monitor any requirements to ensure that s/he can test to see if they’re fulfilled. The tester should block any vague statements such as “user-friendly” or “efficient” or “fast”—to take just one example.
Moreover, requirements are “gathered” in many ways besides an official requirements gathering phase, so the tester must always be on the alert for any way requirments can creep into the project. For instance, developers frequently make assumptions based on their own convenience or preferences, and such assumptions are not usually documented. Or, salespeople make promises to important customers, or put promises in advertisements, so a tester must spend some time speaking (at least informally) to customers—and also reading ads.
In short, a tester must be involved right from the very first moment a project is imagined, with eyes, ears, and, yes, nose always on the alert for what must be tested, how it must be tested, and whether or not in can actualliy be tested. That's the way a tester "helps" the requirements gathering and all other phases of a project's life, on alert for anything that could affect accurately documenting the state of the system.

As a consequence of this broad view of the tester's job, a tester has to resist any assertion that "you don't have to be involved in this phase," regardless of what phase it is. Obstacles to testing can arise anywhere.


Sunday, May 22, 2016

How can I be a faster programmer?

Recently, "Tommy" posted the following question on Quora, a question-answer site with lots of good stuff (and some really cheesy stuff) on a variety of topics:

How can be a faster programmer?

Tommy received a goodly portion of excellent answers, with lots of details of tips and techniques—great stuff. Reading them over, I saw that a few of the answers offered some good high-level advice, too, but that advice might be lost in all the details, so I decided to offer a summary high-level view of what I've learned about speedy programming in my 60+ years in the computer business.

First of all, read all the great answers here on Quora and incorporate these ideas, one at a time, into you programming practices. In other words, to become faster or better in some other way, KEEP LEARNING. That’s the number one way to become faster, if you want to be fast.

Second, ask yourself, with each job, “Why is programming speed so important for this job?” Often, it’s an unskilled manager who knows only a dangerous amount about programming, but can always say “work faster.” So ask yourself, what’s an appropriate speed for this job, given that speed and error are tightly related.

Third, ask yourself, “Do I really need a program for this problem?” If you don’t have to write a program at all, that gives you infinite speed. Sometimes you don’t have to write a program because one already exists that will do an adequate job. Sometimes you don’t have to write a program because a back-of-the-envelope estimate will give all the answers needed. Sometimes you don’t have to write a program because there’s no real need for the function you’ve been asked to implement.

Fourth, don’t skimp on up front work because you’re rushing to produce code. If you’re working with the wrong requirements, any nifty code you write will be worthless, so any time you spend on it will be wasted. If your design is poor, you’ll write lots of wasted code, which means more wasted time.

Fifth, when you finally have a good design for the right requirements, slow down your coding in order to go faster. We say, “Code in haste; debug at leisure.” Take whatever time you need to think clearly, to review with your colleagues, to find solid code you can reuse, to test as you build incrementally so you don’t have to backtrack.

Sixth, develop in a team, and develop your team. If you think teammates slow you down, then it’s because you haven’t put the effort into building your team. So, in fact, we’re back to the first point, but now at the team level. Keep learning as a team. Your first job is not to build code, but to build the team that builds code.

Many of these principles are developed in much more detail in my many books on software development, so if you want to learn more, take a look at my Leanpub.com author page and make some choices among about fifty books and a bundle of bundles of books. Good reading!

Tuesday, May 05, 2015

Requirements Hints and Variations

In both volumes of Exploring Requirements, we follow each chapter with a section of hints and variations about the topic of the chapter. Many readers tell us that this extra material is often more valuable than the chapter body itself. For that reason, I've decided to present a blog entry consisting entirely of  the hints and variations from the first chapter of Volume One. Enjoy!


(1) Another source of complexity in development projects is the desire of non-experts to be involved in the design of complex products. Most customers naturally prefer to learn as little as possible about product design, yet still have all their wishes met in the requirements process. When customers prefer to remain naive about the product design process, most of the burden falls on the notation—a lot to ask of a notation. The design complexity problem can be solved by creating a tutorial to convert a naive customers into an expert—but not if the customers doesn’t want to invest that kind of effort.

(2) Customers often turn away from the design process because the professional designers treat them in a patronizing manner. Remember, most participants are naive only about the development process, and are themselves experts in subjects about which the designers are naive. Such expertise is why their participation is essential. We’re much more likely to have their full participation if we create an environment of shared expertise.

(3) Methodology experts underestimate the difficulty of understanding their nota- tions, which they believe to be “intuitive.” To understand how difficult it really is to define an “intuitive” notation, consider the problem of designing universally understood international road signs.

(4) When two sets of experts participate in the same requirements process, there’s often a conflict about which notation is intuitive. Children reared in Paris think French is intuitive, but children reared in Montreal may think both French and English are intuitive. In the same way, experts often share a “first love” syndrome for notations. This first-learned-first-loved bias can be prevented in the same way bilingual children avoid a bias for one language. If you are teaching a notation, instruct your students in two at the same time. Do all maps in both notations, and compare the pair of maps explicitly.

(5) Mastery of the notation may give one party dominance in the requirements process, while excluding those who haven’t mastered the notation. To avoid political wars, you must devote attention to depoliticizing the language issue. Try following the Swiss example: All “first love” notations of participants are declared to be “official” languages of the requirements process. Every official document must be presented in all of the official languages before the process is considered complete.

(6) Although this multilingual approach may seem burdensome, the Swiss example shows it can work if done in the right spirit. Indeed, in Swiss meetings, people from the “dominant” language group often present their ideas in the “secondary” languages, as a courtesy to the minority participants and as a strong indication of how much they value their participation. In our experience with requirements work, this multilingual approach always yields a more accurate definition of requirements as well as a more complete involvement of all participants.


(7) Our colleague Eric Minch suggests a theoretical model: all descriptions of the de- signed system—including the various constituencies’ requirements and satisfactions, the constraints and decisions, and the final specifications for implementation—can be considered statements in different “languages.” In other words, instead of seeing all of these as different descriptions in a single language, we can think of them as the same description in different languages. The full design task then involves finding a way of translating among these languages, and the final product is such a translation strategy.

(8) Minch’s idea stimulated us to recall “translation” is not quite the simple one-to-one task we often assume. Some translations are works of art in themselves, like Edward FitzGerald’s English translation of The Rubaiyat of Omar Khayyam. Consider the famous quatrain:

A Book of Verses underneath the Bough, 
A Jug of Wine, a Loaf of Bread—and
Thou Beside me Singing in the Wilderness—
Oh, Wilderness were Paradise enow!

What part is original with Omar the Tentmaker, astronomer and mathematician from eleventh century Persia? What part has been added (or subtracted) by FitzGerald, the nineteenth century Suffolk gentleman? What part has been added by twenty-first century readers, such as us?

(9) Experiencing the final product, we don’t so much care if it’s an exact translation, but only whether we like the product. This verse reminds us: value can be added at any stage of the product development cycle. Requirements are merely a guide. They are to be taken literally, but not too literally. There are many roads to Paradise.

(10) These observations connect directly with a remark by Ken de Lavigne, our colleague at IBM: “Your discussion of maps brings out the great problem introduced by ‘stepwise refinement’ approaches: although they claim to postpone decisions until the time comes to make them, in fact the most far-reaching decisions are made first, when one has the least amount of information.” Always be prepared to go back and revise the “translation,” or “map,” when further exploration shows there was a wrong branch higher in the decision tree. To do this, let go of the idea of the “one right way,” or “the perfect translation.”

Extra Hint
To see an annotated catalog of all of Jerry's ebooks and bargain bundles, visit https://leanpub.com/u/jerryweinberg

To see a list of most of his books, ebooks and bound books, visit http://www.amazon.com/-/e/B000AP8TZ8

Sunday, April 26, 2015

Ending the Requirements Process

This essay is the entire chapter 5 of the second volume of Exploring Requirements.
The book can be purchased as a single volume, or volumes 1 and 2 as a bundle, or as part of the People Skills bundle. It's also available from various vendors with both volumes as one bound book.



The Book of Life begins with a man and woman in a garden. It ends with Revelations.—Oscar Wilde, A Woman of No Importance
25.1 The Fear of Ending
The requirements process begins with ambiguity. It ends not with revelations, but with agreement. More important, it ends.
But how does it end? At times, the requirements process seems like Oscar Wilde when he remarked, "I was working on the proof of one of my poems all the morning and took out a comma. In the afternoon, I put it back again."
A certain percentage, far too large, of development efforts never emerge from the requirements phase. After two, or five, or even ten years, you can dip into the ongoing requirements process and watch them take out a comma in the morning and put it back again in the afternoon. Far better the comma should be killed during requirements than allowed to live such a lingering death.
Paradoxically, it is the attempt to finish the requirements work that creates this endless living death. The requirements phase ends with agreement, but the requirements work never ends until the product is finished. There simply comes a moment when you decide you have enough agreement to risk moving on into the full design phase.
25.2 The Courage to End It All
Nobody can tell you just when to step off the cliff. It's simply a matter of courage. Whenever an act requires courage, you can be sure that people will invent ways of reducing the courage needed. The requirements process is no different, and several inventions are available to diminish the courage needed to end it all.
25.2.1 Automatic design and development
One of the persistent "inventions" to substitute for courage is some form of automatic design and/or development.
In automatic development, the finished requirements are the input to an automatic process, the output of which is the finished product. There are, today, a few simple products that can be produced in approximately this way. For instance, certain optical lenses can be manufactured automatically starting from a statement of requirements.
In terms of the decision tree, automatic development is like a tree with a trunk, one limb, no branches or twigs, and a single leaf (Figure 25-1). With such a system, finishing requirements is not a problem. When you think you might be finished, you press the button and take a look at the product that emerges. If it's not right, then you weren't finished with the requirements process.
pastedGraphic.png
Figure 25-1. Automatic development is like a tree with a trunk, one limb, no branches or twigs, and a single leaf.
No wonder this appealing dream keeps recurring. It's exactly like the age-old story of the genie in the bottle, with no limit on the number of wishes. For those few products where such a process is in place, the only advantage of a careful requirements process is to save the time and money of wasted trial products. If trial products are cheap, then we can be quite casual about finishing requirements work.
25.2.2 Hacking
Automatic development is, in effect, nothing but requirements work—all trunk and limb. At the other end of the spectrum is hacking, development work with no explicit requirements work. When we hack, we build something, try it out, modify it, and try it again. When we like what we have, we stop. In terms of the decision tree model, hacking is not a tree at all, but a bush: all branches, twigs, and leaves, with no trunk or major limb (Figure 25-2).
pastedGraphic_1.png
Figure 25-2. Hacking is not a tree at all, but a bush—all branches, twigs, and leaves, with no trunk or major limb.
Pure hacking eliminates the problem of ending requirements work, because there is no requirements work. On the other hand, we could conceive of hacking as pure requirements work—each hack is a way of finding out what we really want.
Almost any real project, no matter how well planned and managed, contains a certain amount of hacking, because the real world always plays tricks on our assumptions. People who abhor the idea of hacking may try to create a perfect requirements process. They are the very people who create "living death" requirements processes.
25.2.3 Freezing requirements
Paradoxically, hacking and automatic development are exactly the same process from the point of view of requirements. They are the same because they do not distinguish requirements work from development. Most real-world product development falls somewhere between pure hacking and automatic development, which is why we have to wrestle with the problem of ending.
Even when we have every requirement written down in the form of an agreement, we cannot consider the requirements process to be ended. We know those agreements will have to change because in the real world, assumptions will change. Some people have tried to combat their fear of changing assumptions by imposing a freeze on requirements. They move into the design phase with the brave declaration,
No changes to requirements will be allowed.
Those of us who understand the nature of the real world will readily understand why a freeze simply cannot work. We know of only one product development when it was even possible to enforce the freeze. In that instance, a software services company took a contract to develop an inventory application for a manufacturer. The requirements were frozen by being made part of the contract, and eighteen months later, the application was delivered. Although it met all the contracted requirements, the application was rejected.
This frozen product was totally unusable because in eighteen months it had become totally removed from what was really required in the here-and-now. The customer refused to pay, and the software services company threatened legal action. The customer pointed out how embarrassing it would be to a professional software company to have its "freeze fantasy" exposed in a public courtroom.
Eventually, the two parties sat down to negotiate, and the customer paid about one-fourth of the software firm's expenses. At the end of this bellicose negotiation, someone pointed out how with far less time negotiating, they could have renegotiated the requirements as they went along, and both parties would have been happy.
25.2.4 The renegotiation process
The freeze idea is just a fantasy, designed to help us cope with our fear of closure. But we cannot fearlessly close the requirements phase unless we know there is some renegotiation process available. That's why agreeing to a renegotiation process is the last step in the requirements process.
Working out the renegotiation process is also a final test of the requirements process itself. If the requirements process has been well done, the foundation has been laid for the renegotiation process. The people have all been identified, and they know how to work well together. They have mastered all the techniques they will need in renegotiation, because they are the same techniques the participants needed to reach agreement in the first place.
25.2.5 The fear of making assumptions explicit
The agreement about renegotiation must, of course, be written down, and this act itself may strike fear in some hearts. Another way to avoid ending requirements is to avoid written agreements at the end of the requirements phase. Some designers are afraid of ending requirements because the explicit agreements would make certain assumptions explicit. An example may serve to make this surprising observation more understandable.
While working with the highway department of a certain state, we encountered the problem of what to do about a particularly dangerous curve on one of the state highways (see Figure 25-3). In an average year, about six motorists missed the curve and went to their death over a cliff. Because it was a scenic highway, it was neither practical nor desirable to eliminate the curve, but highway design principles indicated that a much heavier barrier would prevent wayward cars from going over the cliff.
pastedGraphic_2.png
Figure 25-3. What should be done about this dangerous curve?
Building the barrier seems an obvious decision, but there was another factor to consider. Perhaps once every three years, with a heavy barrier in place, one of these wayward cars would bounce off the barrier into a head-on collision with an oncoming vehicle. The collision would likely be fatal for all involved.
Now, on average, the number of people killed with the barrier in place would be perhaps one-fifth of those killed without the barrier, but the highway designers had to think of another factor. When a solo driver goes over the cliff, the newspapers will probably blame the driver. But what if a drunk driver bounces off the barrier and kills a family of seven who just happened to be driving in the wrong place at the wrong time? The headlines would shout about how the barrier caused the deaths of innocent people, and the editorials would scream for heads to roll at the highway department.
So, it's no wonder the highway engineers didn't want anything documented about their decision not to build the barrier. They were making life-and-death decisions in a way that covered their butts, and they could protect themselves by taking the position, "If I never thought about it, I'm not responsible for overlooking it in the design." And, if it was never written down, who could say they had thought of it?
25.3 The Courage to Be Inadequate
Most engineers and designers react to this story by citing similar stories of their own to prove, yes, indeed, there are decisions it's better not to write down. We believe, however, this kind of pretense is an abuse of professional power, an abuse not necessary if we remember the proper role of the requirements process.
It's not for the designers to decide what is wanted, but only to assist the customers in discovering what they want. The highway designers should have documented the two sides of the issue, then gone to the elected authorities for resolution of this open requirements question. With guidance from those charged with such responsibilities, the engineers could have designed an appropriate solution.
But suppose the politicians came back with an impossible requirement, such as,
The highway curve must be redesigned so there will be no fatalities in five years.
Then the engineers would simply go back to their customers and state they knew of no solution that fit this requirement, except perhaps for a barricade preventing cars from using the highway. Yes, they might lose their jobs, but that's what it means to be a professional—never to promise what you know in advance you can't deliver.

The purpose of requirements work is to avoid making mistakes, and to do a complete job. In the end, however, you can't avoid all mistakes, and you can't be omniscient. If you can't risk being wrong—if you can't risk being inadequate to the task you've taken on—you will never succeed in requirements work. If you want the reward, you will have to take the risk.