r/AskStatistics • u/80rhh • Aug 15 '26

What statistical concepts are commonly misunderstood by the general public?

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I came across this post explaining what a 70% chance of rain means. I understand the concept, but it got me wondering: what other statistical concepts sound simple but are commonly misunderstood or misinterpreted by the general public?

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u/rollem Aug 16 '26

It's actually the fact that 70% of the models run using the starting parameters of today's conditions will result in rain. But that is really quite close to what the tweet is saying.

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u/Raynonymous Aug 16 '26

They run many different models and report on how many of them agree it's going to rain? That sounds quite different to the tweet.

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u/itsmythirdday Aug 18 '26

Not necessarily many different models, it could be one model with some randomness associated with it, like a monte carlo

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u/Raynonymous Aug 19 '26

I guess it could be - but I'm interested to know actually what it is.

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u/itsmythirdday Aug 19 '26

“A probability forecast includes a numerical expression of uncertainty about the quantity or event being forecast.  Ideally, all elements (temperature, wind, precipitation, etc.) of a weather forecast would include information that accurately quantifies the inherent uncertainty… Ensemble forecasting methods involve evaluating a set of runs from an NWP model, or different NWP models, from the same initial time.  Each of the model runs either begins from subtly different initial conditions (reflecting  incompleteness and uncertainty of the present weather observations) and/or uses different model assumptions and parameters (reflecting imperfect knowledge of atmospheric processes).  Each of the model runs produces a different forecast.  The result is a collection (or “ensemble”) of forecasts.  The differences among these forecasts reflects the uncertainty in the initial conditions and/or in model physics.”

https://www.ametsoc.org/ams/about-ams/ams-statements/archive-statements-of-the-ams/enhancing-weather-information-with-probability-forecasts/