Wednesday, April 23, 2008

US government weather service regularly lies, admits lying

The National Oceanic and Atmospheric Administration (NOAA), a branch of the US government, admits to deliberately lying in their weather forecasts.

No, really. In
this Freakonomics blog post, J.D. Eggleston reports on his very interesting statistical study that found that weather forecasters aren't very accurate, especially when it comes to predicting rain. When he asked the NOAA about it,

... [NOAA] meteorologist Noelle Runyan ... stated, "Our forecasts are more conservative than the television stations. We raise our P.O.P. predictions to over 50 percent only when we are sure of rain."

So when the government determines, to the best of its scientific ability, that there's a 70% chance of rain, they will *at best* tell you there's a 49% chance. Even when there's a 90% chance, they'll still quote you 49% or less.

I wonder if Runyan misspoke ... a literal reading of her statement suggests that NOAA will NEVER predict anywhere between 50.1% and 99.9%. I suppose you could check whether that's really true.

Still, calling an estimate "conservative" usually applies when you're trying to make an argument, and you're showing that even if you err towards the opponent's side, your position still holds. That's not the case here. If what Runyan says is correct, I would characterize the NOAA's predictions not as "conservative," but as "false."



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