In project management there’s a model known as the triple constraint or the iron triangle it says that the quality of something that you delivery is governed by a balancing of the scope, cost and schedule. If you want it fast then it will cost you more, or you need to reduce the scope that can delivered.
The same principle is summarised in an old axiom:
Fast, Cheap, and Good…pick two.
The big idea is that you need to balance out what you want because you can’t have it all.
In my experience, though, we aren’t very good at this balancing, we tend to be quite simple creatures and only have the ability to focus on one objective, this leads to tyranny by the one we choose over the other two. Most commonly it’s a tyranny of cost but increasingly increasingly I’m seeing a tyranny of schedule.
There is often little discussion about which one is the chosen one, it’s normally chosen subconsciously by the organisational culture or the commissioning part of the organisation. If the project is Finance driven then cost is chosen, if the project is needed by the production part of the business then the schedule is sometime chosen. Sometimes it’s clear that schedule has to be the chosen one, because something is required for a set date, but that’s not the norm.
As we live under the tyranny of one of these triple constraints we live in the expectation that the other two will come dancing along behind to join the party even though they are uninvited guests. We hope that cost and scope will be good enough as the schedule consumes our attention. We hope that the schedule and scope will fit as we focus in on the costs. Every now and then we turn around and create a new baseline making the triumvirate fit together, in theory, whilst continuing to give our attention to the chosen one. This process normally results in scope handing over pieces of its land to assuage the chosen one.
So how do we resolve this problem? Do we just need to pick a different constraint, hand the power over to a different tyrant and hope that they are better leaders? I’m not sure that any are better than the others, I’ve seen projects run with each as the chosen one and each of them miss out the other two, none of the constraints are very good collaborators. No, I think that the answer is to recognise that which ever gets chosen will become a tyrant, and that the way to deal with a tyrant is to limit their territory. That’s one of the fundamental differences between Agile and Waterfall project approaches. In Agile the tyrants influence is limited by the sprint, once a sprint is finished you can hand the priority over to one of the other members of the triumvirate. The smaller chunks limit the grip of the chosen one. Having said that I’ve seen many Agile projects set up with the schedule as the tyrant. A sprint is, after all, defined as a unit of time within the schedule.
Graham Chastney 