Topic 1.7: The triple constraints
Others more dramatically refer to them as the ‘iron triangle’ (a term coined by Dr Martin Barnes in his course ‘Time and Money in Contract Control’ (1969)).
At the centre of this triangle is quality. It’s at the centre because changes to time, cost and scope all impact upon (or constrain) quality.
As project managers, we often use this triangle to illustrate why agreement on these factors is necessary, and how seemingly minor changes to scope, time or cost can have significant repercussions.
Let’s see how…
“Work expands so as to fill the available time for completion.”
C. Northcote Parkinson (1909-1993)
Note that we have been using words like “potentially” and “likely” throughout this discussion.
Parkinson’s Law suggests just giving more time to a project might only result in people dropping their productivity to fill the slack.
Similarly, if you give one project $5000 to complete the work and an identically scoped project $10,000, chances are they will both find a way to spend all of their budget!
Changes to scope, time and cost will only change the quality of the deliverables by default if there is no management intervention; and this is where the skill of the project manager comes in.
For example, a poorly defined scope – and by that we mean we only have a vague idea of what it is we are setting out to do – is far less likely to deliver a quality outcome than a slightly more complex project that is really well defined, understood and agreed to.
Similarly, an experienced and effective project manager will usually be able to do more with less. In other words, given the same constraints as a less experienced and effective colleague, he or she should be able to deliver a higher quality product, service or result.
Quality as an outcome refers to whether or not our deliverable or output meets the client’s requirements.
In other words, does it do what we said it would?
Quality as a process not only includes how we manage time, cost and scope, but other related activities such as risk and stakeholder management.
This process, that some refer to as integration – that is, the way we bring all the process elements together – is essentially what project management and this course are all about.