## Pandemic blog 5: exponential

When do you go the grocery store? If you’re concerned about your own risk of infection, the logic of exponential growth insists that today is always better than tomorrow. But the community is better served by each person waiting as long as they can, so as to slow the overall exponential constant.

What is the exponential constant? People are constantly graphing the number of confirmed cases in each country, state, locality on a log-linear scale and watching the slope, but I don’t see how, in a principled way, to untangle the effects of increased testing from actual increases in infection. I guess if one hypothesizes that there’s something like a true mean rate you could plot state-by-state nominal cases against tests done and see if you can fit exp(ct)*(tests per capita) to it. But there are state-to-state differences in testing criteria, state-to-state differences in mitigation strategy, etc.

AB and I made chocolate chip cookies today. Dr. Mrs. Q and CJ watched Inside Out. Weather’s warmer and I think we’ll get some driveway basketball in. We listened to “The Gambler” in honor of Kenny Rogers, deceased today. I had forgotten, or didn’t know, what an ice-cold love letter to death it is. “Every hand’s a winner, and every hand’s a loser, and the best that you can hope for is to die in your sleep.” Damn.

Tagged , ,

## 6 thoughts on “Pandemic blog 5: exponential”

1. How often do you go to the grocery store? I’ve been once in the last two weeks last Wednesday. They had been inundated the previous weekend but were basically completely stocked except for tofu and yeast. I spent almost \$300, even though I usually barely break \$100 for 5 days food for everyone at the same store. I’m wondering what to do in a week or so when the fresh veggies run out. (I would guess that the same food from Whole Foods delivery would cost over \$600 and most of the produce would not be as good, let alone the issue of whether they are stocked.)

2. JSE says:

Usually once a week. I made several stock-up trips about a week ago, the last one on Monday.

3. I guess I meant, “how often do you plan to go now” rather than “usually”. Are you all going to stretch it as long as you can on beans and rice, or are you still going to brave the store for veggies and fresh meat, or are you getting delivery?

4. JSE says:

My vision is that I’m gonna go. Even in places with very stringent lockdown they are not telling people not to go to the grocery store. I am reducing the number of times I’m inside a building with people unrelated to me by, what, 95% as it is? I don’t think the difference between 5% and 0% matters a lot from a public health perspective. It matters more from a “personal risk of infection” perspective which is a secondary concern but definitely not NOT a concern. I have to investigate how grocery delivery works here; I’ve never used it. I guess my calculation is that if grocery delivery is working smoothly here, I might as well use it, while if it’s overburdened and slow, I should leave it for people who have a more primary need to protect themselves from potential infection. Feel free to say if this computation seems wrong; I’m making it up as I go. We certainly have enough calories in the house to hang out for a while without shopping.

5. Deaths seem like the better thing to fit exponentials to, since testing is typically reserved for severe cases in shortages and so one can expect most to all of the COVID-19 deaths to be counted accurately (or, at least, that the fraction which are accurately measured doesn’t change too much over time).

6. ventullo says:

I went to Whole Foods earlier this week and a higher-than-average proportion of shoppers were from Prime Now doing delivery. It makes me wonder: would it be systemically safer or riskier to have a small number of people doing the shopping for everyone? I guess it depends on how transferable infection is via mutual contact with boxes and produce.