One of my most memorable job interviews ever was one in which I was asked to come up with an answer on the spot to this question: “What are the odds that there are at least two people who live in New York City and have the exact same number of hairs on their heads?” *

It was a programming job; the interviewer was looking for a display of a rational problem-solving. Nonetheless I compulsively said the first thing that came into my head: “One hundred percent. I personally know two bald New Yorkers.”

Smart aleck. I got the job offer, but I knew I hadn’t really demonstrated the thinking they were looking for. I’ve just started a cool book called Guesstimation: Solving the World’s Problems on the Back of a Cocktail Napkin. If I’d read this then, I’d have had the tools to think through that question in the way I suspect the interviewer had hoped.

We’re doing some interesting guesstimation at Yankee Group right now, though, so it will come in handy. As part of some work we have underway to assess the scale and pace of the emergence of ubiquitous connectivity — what we call Anywhere — we’re sizing its impact today and in future. I’ll post again here in a few weeks when it’s finished, so you can see what we have come up with and share some feedback. But at the moment the project is reminding me of the basic challenge of predicting the future: combining art and science in just the right measures. As the book’s authors point out, too many decimal points in a forecast ”are like lying,” since they suggest a level of precision and confidence that these methods can’t possibly offer up.  We’ll round the numbers up to the nearest hundred billion, I promise…

* The current population of NYC is over 8 million, and the average human has 100,000 hairs on his head. so you figure it out.