Friday, August 6, 2010

50/50 estimate

I was taking a look at a new blog, Project Junction, and came across a bit that says that microsoft project assumes that when you estimate time that you estimate that it is a 50/50 chance that it will be correct. The blog goes on to say:
Very few people give you a 50/50 estimate when you ask for a task duration. Unless you train the estimators each person will give you their personal estimate based on his/her risk tolerance. It might be a 90% estimate from Ms. Risk Averse and a 30% estimate from Mr. Everything’s Easy.

I know that you can give the same set of drawings and infromation to multiple people and you will get different answers from everyone, but I am not sure that I think estimating to a 50% chance of meeting a deadline really works in our world where the deadline is less than flexible. This creates the challenge in estimating hours - it is easy to estimate a safe number of hours that will allow you to get the job done. And if you are held to the hours that are estimated, the hours will naturally lean towards less risk. It is hard to estimate tightly - where there is enough hours to complete, but the hours must be efficient and effective.



  1. Its all a balance game. This is where personal experience comes into play - what separates the pros from the newbs. I suppose some people just have a natural knack for accurate estimates, but I've never met one. By and large most of us learn to gauge our own estimation accuracy and compensate accordingly. I'm sure some people make these adjustments consciously, and others by gut feeling - without even knowing that they are compensating.

    Those who don't yet have that experience usually end up eating the extra cost or losing the bid. Unfortunately, it happens all the time, I know I've done my fair share of "oh crap" late night calls, as has everyone I've ever worked with. (All in the past I assure you, we're all perfect now.)

    As the complexity and convoluted-ness of the project increases, the estimation accuracy usually decreases - unless you've got the requisite experience to gauge how much you don't know about the project.

    As for the 50/50 figure, I guess that's the best shot in the dark from the lot. Some people over-compensate & some under-compensate. 50/50 sure is the perfect medium between not enough resources and too much, which is probably why they chose it.

  2. Thanks for the comment.
    I think one of the important aspects of improving accuracy is the ability to have feedback about how the project played out that you can compare to what was orginally estimated.
    For complex projects, I suppose estimating depends on what you don't know. If I know something is a graphic, I can give a pretty safe SF price, and not know what the graphic is. If I don't know how much scenery there is - I can give a rom - Approx X SF will cost X, and finalize the budget after design has been solidified. Other projects involving research and testing can be tricky. An effect might be easy, or very difficult. Outside of theatre I can give an allowance to solve the issue, and then we can reevaluate it in process and see if a change order is necessary. In theatre, I have seen this in practice as well, it just doesn't use the same language.