ANSWER

Most people are very familiar with the adage that “a picture is worth a thousand words”. This adage is virtually universal because it touches upon two simple, fundamental tenets of human memory and thought processing. These two tenets are also the reason why diagrams, models and visual aids have become invaluable tools for Business Analysts:

• Short-term memory capacity: The average person can process about 7 objects (plus or minus 2) in short-term memory (“Miller’s Law”). The magic of seven is pervasive: phone numbers (7-10 digits), government-issued IDs (often 7-9 digits), vehicle license plate numbers, etc. This limit on short-term memory affects how well an audience comprehends and utilizes information provided to them – whether verbally or in writing.
• Pattern processing: The human mind is designed to work with patterns, rather than individual pieces – this is the underlying principle for most optical illusions. Our brains fill in the gaps to make a pattern that is familiar, or that makes sense. People are very efficient and effective when processing new information that fits within a recognizable pattern. It takes much more time and effort to understand and assimilate disparate, discrete pieces of data.

Both principles come together in diagrams and models. Grouping related items (whether requirements, ideas, business processes, etc.) into a diagram or model is just a way of forming them into recognizable and (hopefully!) familiar patterns. And the short-term memory limit is much less constraining if people are asked to remember and absorb a few different patterns as opposed to dozens of individual bits of information.

These two tenets explain why it is very difficult for stakeholders to simply spiel off a list of requirements, or to review lists of requirements and identify anything missing or incorrect. It is simply too much information to process in short-term memory, and lists (even well-organized ones) do not reap the benefits of pattern recognition. However, stakeholders can look at diagrams and models, and find gaps where the pattern is incomplete or incorrect.

The model or diagram must clearly show relationships between objects, and related objects must together form a single theme or concept in order for the viewer to recognize patterns.

There are many different modeling and diagramming techniques in the Business Analyst toolkit, for a reason. Each one shows different types of relationships and contains different sets of information – and therefore produces different patterns. A combination of diagram or model types may work best on medium-to-large projects. Ideally, the one chosen at any point should mimic the patterns and relationships that stakeholders use to organize their work world. For example, people perform work activities in order to achieve some goal or end-state – so process models or workflow models are good ways to organize tasks and activities into functional patterns. Decisions are a logical way to group business rules, so decision models and matrices are a good way to create patterns from rules. Data is collated and organized into information, so data flow diagrams can identify patterns in the way that information is compiled and shared (but data flow diagrams cannot describe patterns of activity or workflow, and cannot show the relationships between rules and decisions). 

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Sandy Lambert
Business Architect
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