Budgeting by Averages

I've posted this before, but people keep asking... so here it is again:

There is an easy formula used by many experienced project managers to estimate the amount of time to be spent on each budget item task. The formula looks like this:

(1O + 4M +1P) ÷ 6

It means one optimistic + four most likely + one pessimistic divided by six.
What does that mean? It’s pretty simple: You create a time estimate based on averaging the information you gather. For example, you can approach a graphic designer and ask, "How long would this take?” The answer is not the most likely number. It’s the optimistic number, because if you ask any creative person how long something will take, the answer is an exaggerated number. Let’s say the number is eight hours.
Then you say, “Well, if it was anybody else, how long would it take?” And that’s the most likely number. For our formula, let’s use 12 hours.
Then ask, "If something goes wrong that you really didn’t count on, what is the worst case scenario?" In this example, use 22 hours.
You then plug these values into the formula to get your result: ((1*8) + (4*12) + (1*22) ÷ 6 = 13 hours for the task.
This budgeting formula works well when no historical data is available for review. It’s also more accurate if you are able to ask more than one person for time estimates. You can then average multiple answers.

This article is excerpted from the Pre-Production chapter in the book Video Made on a Mac: Production and Postproduction Using Apple Final Cut Studio and Adobe Creative Suite.