Information Systems Development

Sidebar: The Quality Triangle

The quality triangle

When developing software or any sort of product or service, there exists a tension between the developers and the different stakeholder groups such as management, users, and investors. This tension relates to how quickly the software can be developed (time), how much money will be spent (cost), and how well it will be built (quality). The quality triangle is a simple concept. It states that for any product or service being developed, you can only address two of the following: time, cost, and quality.

So why can only two of the three factors in the triangle be considered? Because each of these three components are in competition with each other! If you are willing and able to spend a lot of money, then a project can be completed quickly with high quality results because you can provide more resources towards its development. If a project's completion date is not a priority, then it can be completed at a lower cost with higher quality results using a smaller team with fewer resources. Of course, these are just generalizations, and different projects may not fit this model perfectly. But overall, this model is designed to help you understand the trade-offs that must be made when you are developing new products and services.

There are other, fundamental reasons why low-cost, high-quality projects done quickly are so difficult to achieve.

  1. The human mind is analog and the machines the software run on are digital. These are completely different natures that depend upon context and nuance versus being a 1 or a 0. Things that seem obvious to the human mind are not so obvious when forced into a 1 or 0 binary choice.
  2. Human beings leave their imprints on the applications or systems they design. This is best summed up by Conway's Law (1968) – "Organizations that design information systems are constrained to do so in a way that mirrors their internal communication processes". Organizations with poor communication processes will find it very difficult to communicate requirements and priorities, especially for projects at the enterprise level (i.e., that affect the whole organization.