Thread by @CherylRofer

Rant on modeling

1. There are a hundred gazillion models out there. Few of their owners have bothered to compare their model to others to see what is working and what isn't.

2. By the standards of the models I've worked with, they are all simple - a few differential equations, a curve fit. I've worked with a hundred or more elementary reactions and then a mass- and heat-transfer model that incorporated those in. (Hint: we had to boil them down to six

3. The only model I have seen that is at all transparent about its parameters is the Imperial College model. All the others I have seen are curve fits. They mumble about social distancing as a variable, but never say which parameter it fits into.

4. All the curve fits are with different functions. At least, back in the day when chemical kinetics was curve fitting, we always used the same function.

5. It looks like amateur hour. Everyone's got their pet model, but they're not telling us what it is.

And a further layer of amateurs on Twitter say solemn words like "assumptions" that they have nothing to back up.

6. I've spent a lot of time on the Imperial College and IHME models. I don't intend to do that for every single model out there.
nucleardiner.wordpress.com/2020/03/21/the…

nucleardiner.wordpress.com/2020/04/07/the…

7. My assumption from here on in is that any model but the Imperial College model is crap until it's explained. With explicit connection of assumptions to parameters.

And mansplaining this thread will get you blocked.

Tyler Cowen (and probably other economists who think they've got something to say) has never looked closely at the epidemiological models, judging from this. His questions are obnoxious. Ignore stuff like this.
marginalrevolution.com/marginalrevolu…