Have you tried to reconstruct DHHR’s calculations for the County Alert System? Here’s how.
Everyone’s anxious for the Saturday updates: What color will Monongalia County be when the state Department of Health and Human Resources posts its weekly County Alert System update?
Families and teachers have a lot at stake, especially with the September 5 weekly update. Green or yellow, students will start school in person on September 8 and 9, and no one is certain how that will go. Orange or red, they’ll have nine weeks of remote learning—a very different schedule to plan for.
It’s the Saturday updates that will determine the following weeks’ mode of attendance. But DHHR also updates daily and, in this week’s daily updates, Monongalia County has bounced around in the yellow—that’s a 7-day rolling average of 3.1 to 9.9 new COVID cases per 100,000 population. It could jump from there to orange on any day. It’s a nail-biter.
But lots of people, us included, are asking: Why, when I do the calculation myself, do I get a different number? “Everybody wants to perform these calculations on their own,” said DHHR Secretary Bill Crouch when Morgantown magazine got a few minutes on the phone with him.
Here’s what we learned.
You can’t just use the number of new cases DHHR reports for Monongalia County each day. If you’ve visited DHHR’s website every day for the past week and logged the number of new cases reported each day for Mon County, there’s a good chance some of those numbers have been revised. Epidemiologists update daily case numbers retroactively as their investigations conclude that this one really turned out to be an Ohio County case or that one from Preston County should have been counted here. It’s routine epidemiological sausage-making that usually goes on behind the scenes, laid bare for us because we’re watching this pandemic unfold in real time.
But you can get the latest numbers. On DHHR’s COVID-19 dashboard, go to the 7 Day Trend tab and use the County Filter drop-down to filter for Monongalia County. In the table at the bottom right, the Cases column shows the current day’s number of new cases for each of the past seven days.
The calculation is simple. You’ve got this, but just to make sure we’re all doing the same thing: Average the 7 days’ numbers, then multiply by (100,000 / 105,612) to make it the average per 100,000 population.
Your calculation might not match yet. The point of this calculation and the color coding is to classify the level of community spread in each county as relatively safe or relatively unsafe for kids to gather in schools. So DHHR makes an adjustment to ensure the calculation’s relevance. Cases among staff members at nursing homes and prisons are considered community spread and are included in the 7-day average calculation—but cases among nursing home residents and prison inmates are considered “congregate spread” and omitted from the calculation. At the moment, DHHR doesn’t show us those exclusions. If there have been no exclusions in the previous week, your number should match DHHR’s. If there have been exclusions, DHHR’s will be lower.
But we may soon get all of the information. In acknowledgement of the community’s interest in duplicating the calculations, Crouch suggested near the end of our conversation, “We might be able to add a column showing the patients and inmates.”
We’re not sure yet that this accounts entirely for the discrepancy—today, August 27, we got 8.52, and they got 5.95. Is there an outbreak we didn’t know about at the Kennedy Center Federal Correctional Institution?
If you’re following Mon County’s placement in the color-coding system day by day, keep an eye on that 7 Day Trend tab. We’ll update as we learn more.
8.28 update: Our calculation matches DHHR’s for the most recent 7-day average: 7.57. Mon County was in the orange on 8.25, according to the past 7 days’ moving averages — that’s how close we are to being in the orange on any given day.