USING TRIZ TO MANAGE YOUR REQUIREMENTS

The Capture, Understanding and Management of Requirements is, very properly, considered to be a crucial element in the life-cycle of a successful project or system. “Getting the Requirements Right” has become a systems-engineering mantra – and with good reason: most project failures can be ascribed, in part at least, to a failure to properly understand and manage requirements. 

As recalcitrant children we were told to eat our greens (“they are good for you”). As responsible adult engineers, we are exhorted to digest all the requirements before we can move onto the sweet delights of the design phase. Along the way we are spurred on by a litany of cheery maxims: “Get it right first time”, “Do it once and do it right”, “Requirements should be clear, correct and complete”. In many ways, we are encouraged to look upon Requirements as wild beasts that must be captured, tamed and securely tied down before it is safe to proceed. 

Much of the thinking behind this rigorous approach is based upon the premise that all the requirements can be known, and once known will remain stable (or, perhaps, predictable) through the project life-cycle. But is the real world like that? Let’s explore the implications of working with requirements that are harder to tie down – those that cannot be fully understood, or that emerge or change during the project life-cycle – and consider some strategies for dealing with them. We will use some TRIZ tools to help tackle both the understanding, as well as some possible solutions to the problem. 

Requirements Change: Where and why does it happen? 

We start by considering the various different circumstances that lead to requirements change and the nature of changes that result. 

We will then use this as framework to consider ways of tackling the problem. This exploration of the source of requirements change is facilitated through the use of the TRIZ ‘Time and Space’ or 'Nine Boxes' thinking tool. This tool helps us broaden our perspective by considering a situation in two dimensions: time and scale. The time dimension is typically represented in terms of past, present and future, while the scale dimension uses the concept of system scale or hierarchy: super-system, system and sub-system. 

We represent this generic scale as a 3x3 matrix, like this: -


Past Present Future 3 x 3 boxes of TRIZ

Each ‘box’ in the matrix relates to a specific partition of the overall situation. By dividing up the situation in this way we gain three important benefits: 

  1. it broadens our outlook by encouraging us to consider all aspects of the situation. 
  2. it allows us to focus on each box, confident that we will not miss out consideration of all of the other boxes. 
  3. it enables us to get both of the above benefits without them conflicting with each other. The nine boxes are both comprehensive in scope and limited to a manageable number. Thus they both encourage divergence, but limit it in a way that allows us to see detail without losing sight of the context and wider implications of the situation. Thus we simultaneously obtain the benefits of divergence (good for considering all the possibilities) and the benefits of convergence (good for focussing our attention and creativity) whilst also retaining an appreciation of the overall situation. 

This ‘nine-box’ or ‘time and scale’ thinking can be applied to many different aspects of a situation, including:

  • Situation understanding – mapping the context of the problem 
  • Problem definition (what do we want vs. what do we have in each box) 
  • Causes mapping (capturing all the possible causes of a problem) 
  • Resource capture (understanding available resources enables us to develop good (more ‘deal’ in TRIZ terminology) solutions to problems 
  • Solution capture (forces to look for solutions in all boxes) 
  • Situation communication (an excellent way of summarising a complex situation in one simple diagram) 
  • We are now using TRIZ to look at this problem and structure our approach to tackling this problem. 

This ‘nine-box’ or ‘time and scale’ thinking can be applied to many different aspects of a situation, including:

  • Situation understanding – mapping the context of the problem 
  • Problem definition (what do we want vs. what do we have in each box) 
  • Causes mapping (capturing all the possible causes of a problem) 
  • Resource capture (understanding available resources enables us to develop good (more ‘deal’ in TRIZ terminology) solutions to problems 
  • Solution capture (forces to look for solutions in all boxes) 
  • Situation communication (an excellent way of summarising a complex situation in one simple diagram) 
  • We are now using TRIZ to look at this problem and structure our approach to tackling this problem. 
thinking in time and scale, time and space with TRIZ

Often it is used in a combination of all or some of the above. The Time and Scale map is a great aid to anyone trying to understand, communicate and then solve a problem.  ....


Read more from page 3 on the PDF document.

Report prepared by:

Andrew Martin
Oxford Creativity


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