Stupid Estimation Tricks 1: The Squeeze

Posted by Robert Merrill on October 2, 2008 under Estimation | Be the First to Comment

Use this to help someone (or yourself) to come up with an estimate when “you have no idea.”

Imagine you just met with a sponsor for a half hour and heard a project vision. She ended the meeting with, “The steering committee meets this Friday, and I need to know about how long this will take. You don’t need to be exact–just a ballpark will do.”

Famous last words.

Being a firm believer in the principle that “estimates should come from people who will do the work,” you convene the three-person team that seems right for this project.

Six deer eyes, staring at the headlights. Here’s where I use a facilitation technique I call “the squeeze.”

“Could you do this in a month?” I ask. I’m met with gales of laughter. I open my notebook on the table in front of them and draw a graph. “OK, one month, no way.”

“How about a year?” I ask. “No problem,” responds the chorus. “They’ll never give us that long.” Cautious Chuck then adds, “And don’t forget all of the data conversion that they say they’ll do, but we’ll end up doing ourselves. It’s not a sure thing.” So I plot another point–12 months, 90 percent. “OK with that?” “Sure,” says Chuck.

“How about three months?” Everyone shifts nervously in their chairs. “Well, if we can code it in Rails, we can reuse most of Waldorf,  and if they’ll drop some features if we get in trouble, we could have something in three months,” says Optimistic Olivia.

“What are the odds?” I ask. “50/50?” “No way,” says the chorus. “One in ten?” “Yeah, that sounds about right.” So I plot another point, and draw a smooth curve.

“Does 50/50 in eight months, and almost-sure-thing in thirteen months sound about right?”

“Sally [the sponsor] is usually pretty reasonable. Working with her, we could have something done in a year, even if we run into data problems,” says Pragmatic Paul. So I adjust the curve a little.

“OK, I’ll tell Sally 8 months 50/50, and that we can commit to 12 months based on what we know now. She understands ranges and won’t sign us up for trouble.”

The Squeeze is useful a number of reasons:

• By starting with a very low number and going to a very high number, it gives the estimators permission to say NO and YES with confidence.
• It also reflects the reality that the estimate is a range, and not a single number, and produces a range as a result.
• It can be applied very early in the lifecycle, even “gleam-in-the-eye” stage, as here.

If you’re supporting a knowledgeable decision-maker (more on that later), you can give them a range directly from The Squeeze. If you know your number will turn into a not-to-exceed, you can use the top end, and then have the 50/50 for your initial project plan.

You can combine The Squeeze with Wideband Delphi if you’re worried about groupthink setting in.