Dear Colleagues,

I know many of you will think I have lost the plot when discussing the KISS principle but it is a vital engineering philosophy. Most of you will know it means: Keep it Simple, Stupid (other variations are Keep it Short and Simple). This should be a key goal in all engineering design. Of course, there is no suggestion that the design engineer or the user of the equipment is stupid. It is just that this is a very effective principle.

In passing, I often say that we should make the product or service orang utan proof (with apologies to the orang utan). Able to be used by anyone under the most stressful and trying of circumstances.

Historically Speaking
Apparently the acronym KISS was first used by Kelly Johnson, the lead engineer for the Lockheed U-2 and SR-71 Blackbird spy planes. His philosophy was that the aircraft his team was designing must be repairable by an average mechanic under highly stressful conditions (war or combat) with a limited set of tools. Other related commentaries have come from Albert Einstein who remarked: Everything should be made as simple as possible, but no simpler; and Leonardo Da Vinci who noted: Simplicity is the ultimate sophistication.

I am sure most of you have been confronted with a design that is simply too complex to be usable. Especially, when the operators having to use it are not highly sophisticated or trained. Or the operators are in a tough environment (e.g. mining or the harsh marine environment) and have limited time for the niceties in operating the equipment.
An area which I am sure most of us have come across are badly designed SCADA operator screens which make it very difficult for an operator to visualize exactly what is going on in the plant. And then when an emergency occurs, the deluge of information makes it very difficult to rectify the situation.

Avoid Creeping
The enemies of the KISS principle are function creep or scope creep. This is especially true in software development. This refers to uncontrolled growth in the scope of the project often due to the user demanding more features or changes. This requirement for changes to the project; generally are not accompanied by any increase in resources, schedule or budget. This generally results in a project which is over budget and  well outside the deadlines for completion. And in the case of software development; it is often associated with a failed software development. The resultant product developed (after scope creep) is often too complex to be usable.

The solution is when developing a product is to be absolutely ruthless in the development to make the product as simple and effective as possible and to avoid all attempts at giving it more features. And in the development process not to allow any changes. Only allow changes when they have been carefully considered and costed and do not make the product more complex.

Not that this is an advertisement for the Apple range of products; but the late Steve Jobs spent an inordinate amount of time in the development of these products (such as the iPod) in making them as simple to use and operate as possible.

Thanks to Wikipedia and the Princeton Review for a discussion on the KISS principle.

Jessie Sampter summarises the situation well: Simplicity is the peak of civilization.

Yours in engineering learning,