This Focused Performance Weblog started life as a "business management blog" containing links and commentary related primarily to organizational effectiveness with a "Theory of Constraints" perspective, but is in the process of evolving towards primary content on interactive and mobile marketing. Think of it as about Focusing marketing messages for enhanced Performance. If you are on an archive page, current postings are found here.
Sunday, July 03, 2005
Estimating Project Durations - Not Deadlines -- Over at Cutting Through, Tim points to and comments on a recent post at Open Loops, in which Bert discusses Estimating Realistic Project Deadlines. Bert offers up the old standard "best case - worst case - most likely" PERT formula as a means to taking variation into account when making project promises. Tim's comment resonates with me...
I’m always a little wary of formulas - when there’s a calculation to come up with an answer, there’s always a temptation to rely on this as a definitive God-given answer that has to be correct to five decimal places - but if people are involved as a factor, there’s a danger that you’re lucky if the answers are accurate to an order of magnitude.
...although my wariness comes from a different direction...the fact that this formula ends up with a single number, which gets plugged into a plan as a single number that translates to the "deadline" of the title of Bert's post. Those deadlines then serve as a "not to exceed" target for the task performer, that if not exceeded, implies success from a duration point of view. "If I get done by such-and-such-a-date, our project will be "on track." The problem is that human behavior kicks in with such a deadline-driven viewpoint, serving as the source of Parkinson's Law. Work will expand to fill the time allowed by that deadline.
When considering task estimates, we should simply face reality and recognize that estimates are best communicated in terms of ranges and best agreed to as such, and not as single point commitments. The idea of "accurate estimates," over which too much time, effort, and angst is too often spent in project planning, needs to be set aside. It must be replaced with a brief conversation about how long (in time or iterations) something might take and how short it could take if good luck and good work practices come together. The former needs to respect the fact that Murphy's Law has not yet been repealed and that there are non-trivial unknowns at the time of planning. The latter highlights what management practices and additional predecessor pieces of the project would benefit delivery speed. The difference between the two is the time value of doing what is necessary to make the shorter time more likely.
From a planning efficiency perspective, this two-point range estimate heads off a lot of unnecessary negotiation, CYA, and other political activity that is associated with "accurate estimates" or "estimates as commitments," and does little but strain the necessary teamwork and trust between the people involved. It does so by respecting the concerns of those who will do the work, and and by providing necessary understanding of the prediction to those for whom speed of delivery translates to more benefit.
And from an effectiveness perspective, it provides the basis for rational predictions and promises; expected not-to-exceed promises bounded by the upper limits of a range of reasonable prediction that is managed, refined and narrowed as the project effort learns more about itself.
View Frank Patrick's profile
