At least two different schools of thought have developed over how to calculate coronavirus data, specifically the daily positive rate.
Early on in the pandemic, Governor Burgum cited this percentage as the number to follow, because it does not go up or down based on the number of tests completed, which varies from day-to-day.
But a highly-cited research university, Johns Hopkins, tracks North Dakota’s daily positive rate differently than North Dakota’s own Department of Health.
Burgum addressed this topic at a recent press briefing.
In reference to JHU, he said, “Which of course is a well-respected brand in medicine. They’re using date from a group called the COVID Tracking Project. The COVID Tracking Project is sponsored by a magazine, the Atlantic. This is not a government sourced thing…That causes me some concern.”
The COVID Tracking Project is a volunteer organization. Its sole mission is to collect and publish coronavirus data for the US using information collected from states.
A team at Johns Hopkins does it’s own calculations using this data, and the project has become a primary source for national news sources too, including NPR and CNN.
So what’s the discrepancy?
Check out this chart:
The state gives out two different numbers each day. The first one shows the total number of tests completed the day before, which includes people who have been retested (whether it was months ago or twice in a week — a common practice to ensure the test didn’t give a false negative or positive).
The second number is total unique individuals from the day before, meaning only people who were tested for the first time
So, to get the percentage of people who tested positive out of a day’s worth of testing, you can use the total or the unique total.
The NDDOH uses total tests. Johns Hopkins uses unique tests, and the result is drastically different:
The Department of Health declined an interview request, but we were able to get some answers from the governor at his weekly press conferences.
He shared, “It doesn’t matter if we tested them last May. If they thought they had symptoms last May and got tested and they were negative, turned out they had a cold…they walk in the door and they get tested today, and they’re positive– then, what? We can’t count them?”
But that doesn’t account for the multiple tests one person is often given in a week to 10 day period.
In a statement to KX News, Johns Hopkins University said, “Currently, states may not be distinguishing overall tests administered from the number of individuals who have been tested. This is an important limitation to the data that is available to track testing in the U.S., and states should work to address it.”
“We’re doing it both ways. When you look at the footnote under John Hopkins, it says that states should report the number of individuals that are tested and the number of total tests. And we’ve been doing that all along,” the Governor explained.
It’s true. Just like we did for this story, you can easily calculate the positivity rate using unique tests from what’s provided on the Department of Health’s website.
At the end of the day, consistency is key in reporting. And no matter which calculation makes more sense to you, the rate of people testing positive each day in North Dakota has been consistently on the rise all month.