Counting to a billion

4-year-old: Daddy, can you count to one hundred?

Me: Sure I can.

4yo, wide-eyed: Can you count to... ONE. THOU. SAND!?!

Me: Yep.

4yo: Wow. How high can you count?

Me: I don't know. Up to a billion, I guess?

4yo: Did you ever count to a billion? How long did it take you?

Me, laughing: That would probably take months!

Above little anecdote reminded me again of how bad we really are at estimating. Sure, if I have to guess the amount of people in a living room, I am pretty sure I will get it right. Or in a classroom, give or take five. But what about the amount of people in a stadium? Or at a music festival? My guess would be most likely a long way off the exact number.

As long as values are pretty low, we feel comfortable using absolute estimates. But the higher the values... or the longer the time... the higher the complexity... the bigger the effort..., the shakier it gets. This is because human brains are programmed to compare; we need a reference. Therefore, we are much better at estimating when we can compare one thing to another.

"I might not know how much Pete is exactly weighing, but he is definitely heavier than Simon."

"Though I don't know how high the Burj Khalifa is, I can tell you that it is much higher than the Eiffel Tower."

This is also why, in Scrum, we often use hours (absolute estimates) for small Tasks, but the Fibonacci sequence or T-shirt sizes (relative estimates) for larger Stories and Epics.

"I might not know exactly how long it will take us to realize Story X, but looking at size, effort and complexity it is definitely larger than Story C, but smaller than Story F."

If it took the team three days to realize Story C in above example, and six days for Story F, it'll probably take 4-5 days to realize Story X.

So.... How long does it take to count to a billion? Frank de Boosere asked himself this very question somewhere in 2012. He wrote a simple program to do the work for him, and it has been counting ever since. Since 2012. Day and night. 24/7. And the counter just passed a quarter of a billion. Boy, was I wrong.