Air Travel Surges by 123%! (Beware of Misleading Data Like That.)

[dalton99a]

https://www.nytimes.com/2020/05/19/upshot/virus-economic-data-upended.html

Air Travel Surges by 123%! (Beware of Misleading Data Like That.)
In normal times, percentage change is a helpful guide to what’s happening in the economy. But these are not normal times.
By Neil Irwin
May 19, 2020

Did you hear about the booming air travel industry? It’s up 123 percent in just the last month!

Technically, that’s an accurate number. Over the seven days ended Sunday, an average of 212,580 people went through U.S. airport security checkpoints, up from 95,161 in the week ended April 17.

But of course, that is all wrong if you know anything about the underlying reality of the air travel industry. This time a year ago, 2.4 million people a day went through those same checkpoints. By any reasonable measure, these remain disastrous times for air traffic. It’s just that the shutdown in March and early April made even the slight recovery that has taken place seem like an enormous surge in percentage terms.

Get ready for the same effect to apply to all sorts of numbers — most notably with economic data. These swings are artifacts of the arithmetic of percentage change. But if you aren’t attuned to the yo-yo effect that we are likely to see in crucial data in the coming months, you could get a misleading impression of where the United States stands.

[Igel]

1. It's the same kind of misuse of stats

found in "coronavirus cases spike in Podunksville, a 250% increase over the two days!" And people say, "Whoa--that's worse than NYC!"

And then it turns out that there were 4 cases on Wednesday and 14 on Thursday, 11 of them resulting from a single laid-back anniversary party.


As for economic numbers, none of them are useful in the way they've been useful to the public at large, and the dirty trick being played on us is when people speak like they are meaningful in the same way (or maybe it's just applied wishful ignorance, who knows?). They show nothing about the health of the underlying economy and foretell nothing discernible. The one thing they can say is that fear and government can shut things down fairly well.

[secondwind]

2. Flying to MIA on the shut-eye from SF.

Was surprised to learn that 115 folks would be on board with me. I will be in FC, hopefully there will be some space