Estimating project work for individual tasks or groups of tasks can be difficult – and it’s important to rely on the project team to either help with estimates or produce the initial estimates that you, as the project manager, then review and document. Is there a sure fire rule of thumb to project estimating? No way. Everyone bases their estimates on guesses, past experiences, and the advice of others…but nothing is perfect and no estimation will ever be 100% dead on…unless it’s by luck.
I do, however, think some people are much better at it than others. I’m of the opinion that estimating is more of a gift – you either have it or you don’t. It’s that ability to think somewhat abstractly on given tasks and figure out with some degree of accuracy what the level of effort will be. Of course, there needs to be a certain level of experience and expertise – but that experience does not always ensure that you’ll give good estimates. Over time, one can learn to be a good estimator, but it helps to have that gift.
From my experience, there are some key weaknesses or traps we can fall into when trying to produce good estimates. Being aware of these in advance can help the PM and team to avoid them, but it still won’t guarantee that you’re producing an accurate estimate. I’ve come up with a list of five that I think are the most common…