Post #954: A trend is a trend until it ceases to be a trend

Posted on January 16, 2021

This is a brief update on trend in new COVID-19 cases, using data reported through 1/15/2021.

By and large, previously-identified short term trends are continuing.  Nationally, we have a little flattening of the curve.  Most states show a downward trend in new cases/ 100,000/ day.  California continues to move sideways.  The only new development is that cases counts have stopped rising in New York.

What I find most notable is how tightly correlated the movements are across states.  It’s not as if a few states are on a downward trend.  Very nearly all of them are, starting very nearly around the same time.

With the holidays now ended more than two weeks ago, it’s hard to think that this is somehow a data reporting or behavioral artifact of that period.  But it’s also hard even to guess what common factor would lead to that coordination.

For example, if you look back to the end of the Thanksgiving data artifact on the first graph below (the first dip in the blue line), the regions were going every-which-way.  Some up, some down, some sideways.  But now?  Now they’re almost all in synch.

I’ve already stated that I think the odds are that we are over the hump (Post #930).  Or so I thought at the new year.  But a trend is a trend until it ceases to be a trend.  We’ll only know the peak when we see it in our rear-view mirror.

Graphs follow.

Nationally, a little flattening of the curve.  Six regions and US (blue line), then all states since 10/1/2020, then all states since start of pandemic.

Midwest and mountain states continue the declines that started in early 2021.    There was a sharp peak in Arizona and Utah, followed by what looks like an equally sharp retreat from that peak.  North Dakota still has the lowest new case rate in the mainland U.S.

The South-Central states appear to be starting in on a coordinated decline in new cases.  Possibly even the South Atlantic (or much of it) shows a similar path.  It’s hard to tell, as the upward trends are fairly modest to begin with.

California continues to go sideways.  New York has at least a temporary plateau in new cases rates.