Post #1156: COVID-19 trends to 6/7/2021: It’s just a data reporting glitch

Posted on June 8, 2021

I’ve analyzed enough health care data to know that this can’t be a real increase in cases.  It has to be a data reporting glitch.  I just have to work out what it is.

Here’s the answer:  This is a result of the Memorial Day.  And it will disappear tomorrow.  The reason is that today’s seven-day moving average actually has eight days’ worth of cases it in, for states that didn’t report data on Memorial Day.

A simple spreadsheet illustrates what’s happening.  Here I’ve represented a day’s worth of new cases with a “1”.  A lot of states didn’t report new cases on Memorial day, but instead reported two days’ worth of cases the next day.  With that reporting pattern, you’ll see a dip in the seven-day moving average reported on Memorial day, and an offsetting jump in the seven-day moving average seven days later.