Saturday, October 03, 2009

Why High-level Measurable Requirements Speed up Projects by Building Trust

(Allow 5 minutes or less reading time)

Stephen M.R. Covey‘s The Speed of Trust caused me to realize that trust is an important subject in the field of Requirements Engineering.

Neither the specification of high-level requirements (a.k.a. objectives) nor the specification of measurable requirements are new practices in requirements engineering after all, just solid engineering practice. However, they both are extremely helpful for building trust between customer and supplier.

The level of trust between customer and supplier determines how much rework will be necessary to reach the project goals. Rework – one of the great wastes that software development allows abundantly – will add to the duration and cost of the project, especially if it happens late in the development cycle, i. e. after testing or even after deployment.

Let me explain.

If you specify high-level requirements – sometimes called objectives or goals – you make your intentions clear: You explicitly say what it is you want to achieve, where you want to be with the product or system.

If you specify requirements measurably, by giving either test method (binary requirements) or scale and meter parameters (scalar requirements), you make your intentions clear, too.

With intentions clarified, the supplier can see how the customer is going to assess his work. The customer‘s agenda will be clear to him. Knowing agendas enables trust. Trust is a prerequisite for speed and therefore low cost.

“Trust is good, control is better.” says a German proverb that is not quite exact in its English form. If you have speed and cost in mind as dimensions of “better,” then the sentence could not be more wrong! Imagine all the effort needed to continuously check somebody’s results and control everything he does. On the other hand, if you trust somebody, you can relax and concentrate on improving your own job and yourself. It’s obvious that trust speeds things up and therefore consumes less resources than suspiciousness.

Let‘s return to requirements engineering and the two helpful practices, namely specifying high-level requirements and specifying requirements measurably.

High-level Requirements

Say the customer writes many low-level requirements but fails to add the top level. By top level I mean the 3 to 10 maybe complex requirements that describe the objectives of the whole system or product. These objectives are then hidden somehow implicitly among the many low-level requirements. The supplier has to guess (or ask). Many suppliers assume the customer knew what he did when he decomposed his objectives into the requirements given in your requirements specification. They trust him. More often than not he didn‘t know, or why have the objectives not been stated in the requirements specification document in the first place?

So essentially the customer might have – at best – implicitly said what he wants to achieve and where he is headed. Chances are the supplier’s best guesses missed the point. Eventually he provides the system for the customer to check, and then the conversation goes on like this:

You: “Hm, so this ought to be the solution to my problem?”

He: “Er, … yes. It delivers what the requirements said!”

You: “OK, then I want my problem back.”

In this case he would better take it back, and work on his real agenda and on how to rebuild the misused trust. However, more often than not what follows is a lengthy phase to work the system or product over, in an attempt to fix it according to requirements that were not clear or even not there when the supplier began working.

Every bit of rework is a bit of wasted effort. We could have done it right the first time, and use the extra budget for a joint weekend fishing trip.

Measurable Requirements

Nearly the same line of reasoning can be used to promote measurable requirements.

Say the customer specified requirements but failed to AT THE SAME TIME give a clue about how he will test them, the supplier most likely gave him a leap of faith. He could then either be trustworthy or not. Assume he decided to specify acceptance criteria and how you intend to test long after development began, just before testing begins. Maybe the customer didn‘t find the time to do it before. Quite possibly he would change to some degree the possible interpretations of his requirements specification by adding the acceptance criteria and test procedures. From the supplier‘s angle the customer NOW shows your real agenda, and it‘s different from what the supplier thought it was. The customer misused his trust, unintentionally in most cases.

Besides this apparent strain on the relationship between the customer and the supplier, the system sponsor now will have to pay the bill. Quite literally so, as expensive rework to fix things has to be done. Hopefully the supplier delivered early, for more time is needed now.


Trust is an important prerequisite to systems with few or even zero defects; I experienced that the one and probably last time I was part of a system development that resulted in (close to) zero defects. One of the prerequisites to zero defects is trust between customer and supplier, as we root-cause-analyzed in a post mortem (ref. principles P1, P4, P7, and P8). Zero defects mean zero rework after the system has been deployed. In the project I was working on it even meant zero rework after the system was delivered for acceptance testing. You see, it makes perfect business sense to build trust by working hard on both quantified and high-level requirements.

In fact, both practices are signs of a strong competence in engineering. Competence is – in turn – a prerequisite to trust, as Mr. Covey rightly points out in his aforementioned book.

If you want to learn more on how to do this, check out these sources:

You can also find related material on Planet Project: