I know John was writing about economic forecasting but the problem of weather forecasting has some similar features - wide range of factors interacting in very complicated ways, complex weather models, gaps in the data, random events etc. Meteorologists across the world are continually comparing results.  The big national agencies continuously compare their forecasts (possibly on a daily basis - I'm not sure), and compare these with outcomes of similar 'starting' positions in the past. These agencies may agree the 'best' model for today, or more likely a longer time scale. So there is a constant looping of data, forecasts and adjustments to models. The weather forecasters publish regular and critical reviews of their forecasting performance - and  they are getting _very_ much better at it. 
The comparison is not entirely spurious; if you're playing the stock market you need very short-term predictions - tomorrow's prices - if you are a pension fund you may need a longer term forecast, if you are Chancellor of the Exchequer ... Oh well. Does all that arid econometrics feed into this, do economists compare forecasts and outcomes (or are these closely guarded commercial secrets)?
Main differences are, I guess, that the weather does not react to the forecast and that the data and science behind meteorology is always getting better.

Anyone interested in mathematical modelling, forecasting (or in very, very big computers) might find meteorological methods of analysis interesting. 

Best forecast for tomorrow's UK weather is 'Same as today'. You have a better than 50% chance of being right as long as you don't say exactly how much rain will fall or how long the sun will shine.

Robert





Professor Robert Moore
School of Sociology and Social Policy
Eleanor Rathbone Building
The University of Liverpool
L69 7ZA

Telephone and fax: 44 (0) 1352 714456
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From: email list for Radical Statistics [[log in to unmask]] on behalf of John Bibby [[log in to unmask]]
Sent: 20 April 2016 17:10
To: [log in to unmask]
Subject: Fwd: Letter: "All forecasts are wrong. But some are more wrong than others" (Derek Jerram,"Forecasting is art, not science", Letters in "i", 2016april20, p.14.

Please see email below - all comments welcome!  JOHN BIBBY

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---------- Forwarded message ----------
From: John Bibby <[log in to unmask]<mailto:[log in to unmask]>>
Date: 20 April 2016 at 17:09


All forecasts are wrong, but some are more wrong than others. Forecasting should not lead to a "precise" number or "point forecast" - like the recent Treasury £4300 in their research on leaving the EU. Instead, it should lead to a "50% confidence interval forecast", such as £4000-£5000 - the interval being calibrated so that the researcher is 50% confident that the forecast is correct. This has the advantage of falsifiability - if an accurate forecasting method is used, exactly 50% of forecasts will be true; the other 50% will be false. (Alternatively, forecasters may choose a wider interval if they require a higher level of confidence e.g. £3000-£6000 with 90% confidence.)

My forecast - most forecasters will not listen to this, because it gives us a way of distinguishing the fraudulent forecasters from the genuine ones.

JOHN BIBBY  (01904-330334<tel:%2801904-330334>)
1 Straylands Grove
York YO31 1EB

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