What diagnosis numbers mean, and don’t mean

One should not generally expect much insight from TV news, but there are exceptions.

One is Vince Vitrano of WTMJ-TV in Milwaukee:

Wisconsin just posted its single largest, daily number of new, confirmed COVID-19 cases. Here’s why that’s not nearly as bad as it seems.
First… my Wauwatosa East High School friends will attest, if my math teacher, Mr. Waala, knew I was dropping math and stats knowledge here… he’d go into cardiac arrest. I was a terrible math student, and I dropped stats in college. Not exactly a glowing self endorsement, but with the help of my TMJ4 News colleagues, we’ve got this thing right.

One of the reasons Wisconsin took such a big jump in cases day to day is because we took a big jump in tests.

The below link has it all. We’ve been asking Wisconsin DHS to do the calculations and put this number front and center, but so far, we’re left to do the math on our own.

Break down:

Yesterday Wisconsin DHS reported 121 new, confirmed cases of coronavirus. Lowest number in a week.

Today, Wisconsin DHS reported 225 new, confirmed cases. Highest single day total ever.

Looks really bad.

HOWEVER, Tuesday’s number is based on 1359 tests. Today’s number is the result of 1886 tests. There were 527 more tests. Naturally one would expect more positive results.

Apples to apples, Tuesday’s number was about 9% positives of the pool of total tests. Today’s number, about 12%. Higher, yes, and not the direction we want to be going, but hardly the huge increase the raw numbers suggest. 3% is not a spike, it’s maybe a bump at most.

Please share the link below with friends, and refer to it often. We will work to update it with new, daily information. It will give perspective as Wisconsin aims to dramatically ramp up testing. Imagine how many positives we’ll get if we start nearing the Governor’s goal of 12,000 daily tests. We’re going to see some big raw numbers of new cases. Those numbers will be of limited relevance. It’s going to be about the percentage of the total… and that’s the metric the State is planning to use as health officials and the Governor determine if we’ve met that criterion for opening businesses again.


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