The Stan project for statistical computation has a great collection of curated case studies which anybody can contribute to, maybe even me, I was thinking. But I don’t have time to worry about that right now because I’m on vacation, being on the yearly visit to my old family home in the north of Sweden.

What I *do* worry about is that my son will be stung by a bumblebee. His name is Torsten, he’s almost two years old, and he loves running around barefoot on the big lawn. Which has its fair share of bumblebees. Maybe I should put shoes on him so he wont step on one, but what are the chances, really.

Well, what *are* the chances? I guess if I only had

- Data on the bumblebee density of the lawn.
- Data on the size of Torsten’s feet and how many steps he takes when running around.
- A reasonable Bayesian model, maybe implemented in Stan.

I could figure that out. “How hard can it be?”, I thought. And so I made an attempt.

## Getting the data

To get some data on bumblebee density I marked out a 1 m² square on a representative part of the lawn. During the course of the day, now and then, I counted up how many bumblebees sat in the square.