The “compass rose” model for requirements gathering

By Gordon Rugg

If you’re trying to find out the requirements for something, whether it’s a dishwasher or an education system, then a key question is how to make sure you’ve identified all the key issues.

One way is the method described in this article. It involves checking for some key points that establish the boundaries for the requirements, as follows

  • Best outcomes
  • Worst outcomes
  • The most common cases
  • The beginning
  • The end
  • Your official remit
  • Your unofficial big picture remit

The image below shows these concepts schematically.

requirements boundaries full

This article unpacks these concepts and identifies suitable methods for handling them.

Best outcomes: What would be the dream outcome?

It’s easy to become focused on low-level, short-term goals. Often, problems become simpler and clearer when you look at the top-level dream goals. They tend to be easier to achieve than people think.

One simple but powerful way of finding out someone’s dream outcomes is by using laddering. In essence, it involves repeatedly asking someone why they would want something, so you’re moving up their hierarchy of goals.

For example, when you ask someone what type of job they would like and why, a common answer from students is that they would like a job with a good salary, so that they could afford to travel.

This means that the higher-level goal here is travel, and that the good salary is a means to that end. A simpler way of getting to that end is to find a job which involves being paid to travel. This looks like a dramatic change in plans, but in fact the higher-level goal has remained unchanged; all that has changed is the route to that goal. It’s a lot easier to achieve the goal of a job in travel than the goal of a job with a good salary.

Usually upwards laddering produces a manageably small number of goals – in the order of half a dozen.

Ethical note: This process very rapidly takes you into people’s core values, so you need to be aware of the potential ethical issues, and to stop asking questions if you have moved into sensitive territory.

Worst outcomes: What do you want to avoid at all costs?

Some worst outcomes are already clearly identified by legislation.

Others can be easy to overlook because they’re so familiar that the stakeholders take them for granted and don’t bother to mention them.

Still others are easy to overlook because they are rare.

Each of these categories requires different approaches, and requires attention to different potential problems.

Legislation might appear to be easy to incorporate into an education model, but in practice, the relevant legislation is often misunderstood or only partly known even by education professionals. A classic example is beliefs about legislation relating to school attendance and to home education.

Taken for granted issues are a widespread problem with requirements gathering in general. They are particularly likely to involve fundamental concepts, that are taken for granted precisely because they’re so fundamental and familiar that it’s hard to imagine them not being there.

Rare cases often have major effects, even though they are rare. Often, they become landmark cases that prompt changes in legislation, with a view to preventing a particular outcome from ever happening again.

The risk here is that the undesirable outcome will be identified correctly, but that the underlying cause will be misidentified, and that the legislation will be trying to fix the wrong problem.

There are various well-established techniques for handling rare cases, such as critical incident technique, which was developed specifically for this type of problem. Scenarios are also useful for working systematically through possibilities that might occur. In addition, laddering can be used to identify undesired outcomes and to unpack the reasons for which they are not desired.

Commonest cases: Which categories account for about 80% of the cases?

There’s a widespread phenomenon known as the Pareto distribution (after the researcher who identified it) or the 80/20 distribution (after the nature of the distribution). Very often, 20% of one thing will account for 80% of something else. For instance, a common finding is that 20% of your product range generates about 80% of your income. Similarly, about 80% of the time that users spend on your website will typically be spent on just 20% of the website.

If you can identify those disproportionate cases, and develop smoothly efficient ways for handling them, then you can significantly reduce the amount of time you spend on them, and significantly increase the amount of time that you can spend on the other cases.

There are various ways of improving processes, whether via process modelling, sociotechnical approaches, physical ergonomics or cognitive ergonomics. Although the names may sound intimidating, the underlying concepts are easy to grasp and apply, and there’s a lot of easily accessible literature about them.

Beginning to end: What is the complete process into which your product or service fits?

It’s a good idea to look at the complete process, because this will often bring out issues that can significantly affect your requirements.

A classic example is a seasonal peak in usage, such as postal services having to cope with a sudden massive increase in demand every Christmas. Similarly, universities and schools have to cope with sudden large influxes of new students every autumn.

Another classic example is remembering to design physical products with forethought about cleaning and maintenance, rather than viewing those issues as someone else’s problem. There’s not much point in designing a product that’s easier to use, if that product will take twice as long to clean or maintain as its competitors.

This relates closely to the next two points, about the boundaries of your remit.

Your official remit: Where do your responsibilities officially begin and end?

It’s wise to check what your official responsibilities actually are, rather than just doing the same as everyone else in the field. Otherwise, there’s a horrible risk that you’ll be caught without a defence when someone sues you for negligence; claiming that everyone else is equally culpable isn’t exactly the strongest position in law. Even if you don’t end up being sued, there’s still a strong chance that you’ll end up having to retro-fix something you produced so that it conforms to a tightening up in enforcement of regulations (e.g. accessibility of web pages for users with visual impairment). It’s better to get it right first time round.

Your unofficial big picture remit: What could you add to your remit to make life easier for everyone, including yourself?

Paradoxically, you can often make life easier for yourself by getting involved with things that aren’t officially your problem.

For instance, if you’re an architect tasked with designing a waiting room for a medical practice, then you might quite legitimately argue that the IT provision isn’t your problem. However, if you talk with the IT provider, you will probably be able to include features in your architectural design that will make things better for everyone – for instance, by designing the room layout so that it’s easy for everyone in the room to see the screen that shows the appointments.

It’s wise to watch out for legal implications if you extend your remit unofficially, since there’s a risk of getting into territory for which you don’t have proper training or insurance. However, if handled with care, this approach of going an extra mile can make life much better for everyone, including yourself.


requirements boundaries full

This is a brief overview of how you can look at the requirements for your product or service from several directions, to improve your coverage of key requirements. You won’t catch all the possible requirements – that simply isn’t possible, since they’re potentially infinite – but your coverage will be broad enough, deep enough and systematic enough to give you a solid foundation.


You’re welcome to use Hyde & Rugg copyleft images for any non-commercial purpose, including lectures, provided that you state that they’re copyleft Hyde & Rugg.

There’s more about the theory behind this article in Gordon’s latest book:

Blind Spot, by Gordon Rugg with Joseph D’Agnese

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