Why were we wrong? There are a number of possible reasons. Was it because the model was the wrong model? Has the model changed? Was our judgemental adjustment wrong? Was our forecast for an explanatory variable wrong? Was there an economic event or ‘shock’ that we didn't anticipate?
http://www.rba.gov.au/speeches/2017/sp-dg-2017-10-26.html  10/16  27/10/2017  Uncertainty | Speeches | RBA  Having attempted to answer these questions, we can then ask what can we learn? What, if anything, do we need to adjust in our forecasting framework? To understand forecast misses, it is important to ask whether there were any unanticipated economic events or ‘shocks’.