Processes in a circle

It is very common for iterative processes to be represented by a circle. A famous example is Deming's Plan Do Check Act:

I was surprised to recently learn that this diagram was actually created by Deming's teacher Shewhart. Anyway a problem with these diagrams is the reader does not know where to start. Let's look at another example from NIEM (National Information Exchange Model) - this diagram is available at NIEM's website.

The labels on each of the stages of the life cycle change their orientation causing the reader to tilt and re-tilt their head. The inputs and outputs from each stage are scattered all over the outside of the circle making it difficult to know what goes into and what comes out of each stage.

Here is the NIEM diagram re-drawn to keep the words in the same orientation and a clearer representation of inputs and outputs:

If you really want to use a circle to show that the process is iterative then consider the following style:

The horizontal arrows allow the reader to see where to start and make it easier to annotate with deliverables. The circle at the end gives force to the concept of iteration.

Some charting websites

Scott Adams, the creator of the Dilbert comic, has a great blog site. Scott's comments are typically interesting and entertaining. Recently he blogged about how useful charts are at explaining concepts and this triggered a huge response from his followers.

I have harvested the following links to sites on charts. Some are great, some are not.

• Ross Perot founded Electronic Data Systems and made two substantial campaigns to become the President of the United States. He has built a fortune worth about $5 billion. He has set up a web site called Perot Charts which makes use of clear, effective charts to provide information about the US economy.
• Graphjam makes amusing charts but they are not clean and crisp. Amusement value only.
• A depressing chart showing similarities between 1929 stock market and today is available here.
• Mark Perry is an economist who makes good use of charts to explain the US economy.

A picture does not always tell 1,000 words

I was on Wikipedia researching information security (yes I am the world's most boring person). Anyway up popped the following picture:

There really should be laws against publishing such hideous diagrams on the web. What if a child should be exposed to such diagrams - they could be scarred for life!

So how do we fix this diagram? Sometimes text can be more powerful than a diagram. Let's try the following:

The three qualities to protect information assets is Confidentiality, Integrity and Availability. These qualities are produced in information systems through hardware, software and communications. Apart from the information system the information assets are protected by policies that guide people on how to use security products.

Comparing lifecycles

The Data Management Body of Knowledge (DM BOK) was released in April 2009 and is well worth reading if you are into that sort of thing. One of the diagrams mapped the stages of the System Development LifeCycle (SDLC) to the Data Lifecycle. This mapping was represented by the following diagram:

This is O.K. but I had some quibbles about the headings appearing in different spots (i.e. above and below the diagram). I also did not like the meaningless variations in colour. The lack of a legend requires the reader to work out that green is used for both the SDLC and the parts of the data lifecycle that map to the SDLC. I also thought the lines that represent the mappings were too thick. I found that other readers did not get the mappings - it was not clear enough for them.

So I have had a stab at re-drawing it with the following (you will need to click on the diagram to read it):

My thinking was to stretch the data lifecycle chevrons to cover the SDLC chevrons. This then removed the needs for the lines and highlights how the data lifecycle extends beyond the SDLC. The use of a legend removes the need for distracting titles. I also chose to keep the chevrons the same colour and shape (the original diagram varies the shapes at the beginning and end of the lifecycle).

What do you think?

Medical illustrations and animations

Betsy A. Palay does great diagramming work for the medical community. Check out an excellent example of using animation to explain medical concepts here.