This news headline sparked my interest. It reads “New York coronavirus deaths on the rise again after temporarily staying flat, Cuomo says.”
Now, I accept on face value that Cuomo said that. What I don’t accept is the truth of it. One data point is not a trend, so it’s absolutely and unequivocally unjustified to say that ‘deaths are on the rise again’. I repeat, this is absolutely and unequivocally unjustified. The future may validate the claim, or it may falsify it. We don’t know yet, and it’s irresponsible to pretend we do.
Here are the facts.
On day N, deaths were 594, on day N+1 deaths were 599, and on day N+2, deaths were 731.
I get that the number today (N+2, April 7, 2020) is higher. OK. What annoys me is that Cuomo, and those who follow his words like the Gospel, can look at a few raw numbers and make pronouncements about trends.
This is a discrete function, folks. The only way we can make reasonable judgments about it is by looking at long term trends, not by looking at individual numbers under a microscope.
For example, suppose that the number of people in New York City who died of rabies each year for the past 10 years was 1. One person per year, steady as a rock.
Then one year, 2 people die of rabies in the same year. Does that mean that the rate of deaths from rabies in NYC has doubled? Holy cow — call out the National Guard! Call the President. Drop to your knees and pray!
Now technically, in some sense, the ‘rate’ has doubled, but only if we understand and accept that the ‘rate’ we are talking about is an inference from discrete and incomplete data. It is subject to statistical fluctuations and most of all to interpretation.
Suppose that we later discover that both of those two deaths occurred in the same week? And in the same town? And in the same house?
Ah, the picture becomes clearer now, as we discover that an elderly couple had a cat, and the cat died of rabies. They didn’t know about the rabies, so they carried it out to the backyard, kissed it goodbye and buried it.
My point is not that this is the same as the death rate in NYC. Just that it pays to consider everything we might want to know about numbers before accepting the hype behind them. And we might want to consider that statistical fluctuations that can lead the unwary into panic.
Remember — the news media has a vested interest in scaring you, because you want to know more about it. That means more viewers, which means more ad revenue, which means more news, which means more hype, which means …. well, you get the picture.