Your friend calls and asks if you want to get some coffee. You’re pretty busy these days, so you say time is tight. “That’s fine. How long will it take you to get to Eva’s Cafe?” You have to answer fast because your friend is waiting and you have to appear vested and interested, and willing to go the extra mile for the relationship.

Case 1: You’ve never been to Eva’s, and you have no idea where it is.

• I know this area reasonably well, so I can probably assume it’s not super close.
• You can get anywhere in the city in less than 90 minutes by train+bus.

Result:

Take the average, round up a little, and you’re left with about 45 minutes to an hour.

Case 2: You’ve never been, but you remember someone saying once that it was in Old Town.

• Old town is just off the brown line, sort of close to the red line. So trains are good.
• There are buses on Wells and Clark, and LaSalle and State St buses go down Clark around there.

Result:

It’s a 10 minute brown line ride from here. Factor in 10 minutes for waiting time, and maybe 5 for walking / looking for the place. About 15 minutes, 20 if you’re cautious.

Case 3: You accept that you have no idea, and wholly put your trust in the Internet. But then you remember what happened last time:

• Google Maps said 16 minutes by bus
• Google Maps said 22 minutes if you walk

The bus is faster, but after 15 minutes of waiting with no bus, you gave up on Google’s schedule. It was sunny, so you decided to walk. By the time you got there 34 minutes later you were sweating and no longer interested in coffee.

Case 4: You realize that in all likelihood you’ll be going to Eva’s on a weekday morning, when the trains are packed.

• Going northbound may not be so bad, since traffic usually heads to the loop
• Express buses only head into the loop, so you can’t rely on those
• It’s possible you’re wrong, and your friend actually wants to meet for cocktails, in which case all of this information could be wrong.

Result: you weigh the odds, assume traffic, and decide to take any of the buses that go down Clark. Because there are several options, wait time is minimal, but the ride is longer than a train. You figure 15 minutes, since the bus stops so close.

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Okay, so in most cases, at this point you have the information you need to make a completely wild guess, because your friend only wants a “rough estimate.” “We can figure out the details later, and I promise we won’t hold you accountable if it ends up being wrong.”

You’re cautious, so you take the biggest estimate and round up. It’ll take an hour, you say, with necessary caveats about unforeseen issues. You’re crossing your fingers for something closer to 15 minutes, because you haven’t eaten breakfast yet and would love some alone time with Tom Waits’ Mule Variations and a muffin.

Now that you’ve hung up, you at last have time to do some research. You get the address, call to confirm they’re open, and check the weather (to see if walking is a comfortable option). To cover all your bases, you check for events in the area, and even check outside for weather about an hour before you leave. All systems go, and you’ll definitely have time for that muffin.

On your way out the door, your friend calls. “Good news!” s/he says. “I’ll pick you up at the Oak Street Beach! We can drive the rest of the way together. See you there at 9!” and hangs up.

There goes your muffin. And your Mule Variations. Worse, the Gold Coast is still pretty far, and strangely it’s not even really on the way.

At this point, your estimate is as worthless as you knew it would be. The only thing you really learned was that the weather is nice (which doesn’t matter because your friend is driving), and the address of the place. You give up and take it easy, and walk to the beach. You show up fifteen minutes late, and your friend is pissed, because sh/e had to drive in circles waiting for you. En route, you discover your friend has no idea where to go, so you feel a little better about having done your research.

By the time you find the place and park, you’re both grumpy. It took you an hour and a half, you still haven’t eaten, and your friend thinks you a lousy pal because you “weren’t committed” and because you said it would only take an hour, and didn’t include parking costs or excess gas from circling at the beach.

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So you’re a software engineer, and are asked for an estimate for a project you don’t know the details of, which will sit on top of software you’ve barely used. The client is on the phone with client services, and they want a “rough estimate” to give the client a quote. “We can figure out the details later, and I promise we won’t hold you accountable if it ends up being wrong.” What do you do?

You tell them to send you more details and you’ll let them know after you’ve done some research.