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SCC 2012 Positively Uncertain; Uncertain Forecast (Peter Gibbs)


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SCC 2012 Positively Uncertain; Uncertain Forecast (Peter Gibbs)

  1. 1. Uncertain ForecastPeter GibbsBroadcast meteorologist, BBC and Met Office© Crown copyright Met Office
  2. 2. Obstacles and AssumptionsWhy are we not communicating it already?• …the public don’t understand probabilities…• …uncertainty is too difficult to communicate…• …the Press don’t get it…• …the Met Office (or BBC) is just covering itself…• …you can’t say 50% chance - that is admitting defeat…• …just tell me what will happen…I just need to make a decision… • or is that “just make my decision for me” ?
  3. 3. Storm of 16th Dec 2011© Crown copyright Met Office
  4. 4. 5-day forecast Both EPSs flag small risk exceptional low over UK EC 944© Crown copyright Met Office Ensemble Training 2012 MOGREPS 938
  5. 5. Forecasters communicate low risk of very high impact• BBC shows two alternative tracks: • Track 1 is low probability but highest impact (severe gales and heavy snow). • Track 2 has a higher probability but lower impact (some snow, but lighter winds).© Crown copyright Met Office Ensemble Training 2012
  6. 6. Max Temp uncertainty 1-5 Feb 2012• Cold block over Europe• Frontal system approaching from Atlantic• Uncertainty about progression BBC Graphic presentation © Crown copyright Met Office Montreal Workshop, March 2012
  7. 7. Decision-making with Uncertainty • There is always uncertainty in forecasts • Recent study in US showed that where uncertainty is not shown, people make own assumptions (Joslyn et al, 2011) • Often over-estimate uncertainty • By explicitly providing uncertainty, people make better decisions •…© Crown copyright Met Office
  8. 8. • Do ensemble forecasts Randomised design cause confusion? Collected basic • Can playersdata demographic make better decisions using Addressing assumptions: Outcomes generated on- ensemble forecasts? “the public don’t understand uncertainty” the-fly (based on • How does this vary with probabilities) “uncertainty is too difficult to communicate” presentation type? Ability to separate 1st time • Demographic players influences© Crown copyright Met Office
  9. 9. Playing the gameHow confident areyou about eachshift – tests ability Choose location or shift – teststo assess ability to understand relativeprobability from probability from presentationpresentation © Crown copyright Met Office
  10. 10. Scoring • Each shift is allocated an outcome randomly selected from the forecast distribution • Element of luck! • Amount of ice cream bought and sold depends on advice and outcome • Total score at end of game:© Crown copyright Met Office
  11. 11. Weather Game – “Engaging online users to gather feedback on the best way to represent forecast uncertainty” -11,000 responses – Largest meteorological survey of its kind -Collaboration with UK Universities – Bristol & Cambridge -Showed that people make better decisions when presented with uncertainty - Consistent across all age groups and educational levels - People made best decisions with the most complex presentations Courtesy of Liz Stephens© Crown copyright Met Office