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.)