Last March I posted a piece on the "Iron Triangle" of project management. It deserves a repeat in light of a discussion on resource management that has started on a forum.

The Iron Triangle is a traditional (although flawed) way to describe the relationship between the independent variables of a project. A Spider Diagram is another notation with more variables. The Spider chart is one way to convey multi-variant information. Add projects contain multi-variant data.

The myth around the Iron Triangle follows the joke of the three variables Cost, Schedule, Quality, pick two. Turns out this myth is too simple in real life - like most myths - to be of much use on anything other than the simplest projects.

So here's the real question(s):

- What are the independent variables of a project?
- What are the related dependent variables, once the independent ones have been identified?
- What is the relationship between the independent variables and the dependent ones?
- Are these linear or non-linear relationships? If non-linear, what are the parameters of the non-linear equations?

Without answers to these the Iron Triangle is just a *notional* description of a complex problem and an easy target for those opposed to such concepts.