Contact
Email is the only channel. I read everything, though replies can take a few days.
Things worth emailing about
- Corrections. A wrong coefficient, a broken slider, a derivation that does not hold. Include the page and what you expected instead.
- Requests. A calculation you keep doing by hand that would be better as a tool.
- Questions about the models. Why a particular assumption is used, or where a coefficient comes from.
It helps to name the page you mean. Each tool page states the model it runs, what that model assumes and what it leaves out, as Monty Hall with N doors does, so the assumption behind a number is already written down where you can point at it.
What I can't help with
I can't do your homework, and I can't tell you whether a number is safe to act on. If something you're building depends on the answer, ask someone who can be held to it.
It's a plain inbox, so don't send me anything you'd mind other people seeing.