Simple Enough?However, what assumptions underlie that estimate? Who did your SME imagine would do that task? Will that person be available? And if so, will that be full time? Did the SME imagine it would take eight hours per day for 12 days, or think they could only be available 2 or 3 hours per day? Is risk already factored into this estimate? Should you add a risk reserve on top of the original estimate? That lonely "12" you are about to enter into your planning software is empty and devoid of context. We assemble hundreds of these estimates to build a schedule, then our tools calculate an end date for the project. Later we are disappointed — but not surprised when the end date begins to slip. Intuitively we know that one of our biggest challenges is the variability of the estimates and the unspoken assumptions behind them, but this is how we were taught to build schedules. We are doing what we were told to do, but we aren't getting the tidy results that the books said we would get. Are we doing something wrong? Well, it's not you. Most scheduling textbooks are wrong, written by smart people well versed in project management theory — but not math! Schedules built using traditional methods are often doomed from the start without acts of heroism, as our real-world experience confirms. There is a way to improve our ability to predict end dates, but first, we have to improve our estimating process and refine how we build schedules.
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Introduction
