Let me take a stab at it because the underlying documentation is truly dense and their spreadsheet only shows values and no formulas:
Take the Positivity Rate and the Case/100k people rates from two weeks ago (because of delays of reporting, the past week's numbers are constantly changing and are usually under-reported). So, e.g.
| County | Positivity % | Cases per 100,00 |
|---|
| Los Angeles | 3.4 "orange" | 10.1 "purple" |
| Orange | 3.2 "orange" | 4.6 "red" |
| San Francisco | 0.8 "yellow" | 2.5 "orange" |
Now, apply modifiers:
If you've been doing a lot of testing in your county/city, with "a lot" being defined as any where up to two times the state median, your "Cases per 100,000" number gets adjusted down depending on how much more than the median you've been testing.
The state median is about 240 tests per 100,000 people.
- Los Angeles has a testing rate per 100k of 386 which reduces its Cases/100k to 75% of its unadjusted value.
- San Francisco has a testing rate of 596 and is adjusted down to 60% of its value.
- Orange has a testing rate of 218. Uh oh... that's *less* than the median. That could mean its testing rate can be adjusted *up*!! However, since it's positivity rate is under 3.5%, it gets off on good behavior, and thus, no adjustment to Cases.
The new standings after adjustments:
| County | Positivity % | Cases per 100,00 |
|---|
| Los Angeles | 3.4 "orange" | 7.6 "purple" |
| Orange | 3.2 "orange" | 4.6 "red" |
| San Francisco | 0.8 "yellow" | 1.5 "orange" |
Next comes the "Equity Adjustment."
The state doesn't want counties to avoid providing testing and caring for its poorest or disenfranchised members. And so, there is a really complicated way to determine what parts of the county are in the 'lowest quartile' (lowest 25% bracket) and to make sure these two things happen:
The most depressed parts of the county have positivity rates that are close to that of the rest of the county.
The most depressed parts of the county have targeted health care plans.
In order to progress to a better tier the difference between the the lowest quartile and the rest of the county needs to be minimized.
So, not caring for the lowest quartile can hold you back, however, caring for the lowest quartile can have rewards!! For even though your county's case rate (per 100k) may not qualify for the next lower tier, if the county as a whole, and it's lowest quartile's *positivity* qualify for the next tier then the county can move into the next tier.
And this kinda makes sense because if you let the virus run rampant in depressed areas (where all your minimum wage employees live), it won't just stay there.
And that's why San Francisco is in the Yellow Tier even though their Cases/100k is still in Orange. That's because the whole city Positivity and their lowest quartile's Positivity are in Yellow (plus all the work they did to show they have targeted health care plans for the lowest quartile).
| County | Positivity % | Equity Positivity % | Cases per 100,00 |
|---|
| Los Angeles | 3.4 "orange" | 5.9 "red" | 7.6 "purple" |
| Orange | 3.2 "orange" | 5.6 "red" | 4.6 "red" |
| San Francisco | 0.8 "yellow" | 1.5 "yellow" | 1.5 "orange" |
www.cdph.ca.gov
