Forecasting the mainland's near-term economic prospects might just have got a little easier, thanks to financial boffins at Nomura who have crunched the numbers to calculate a brand new "China growth surprise index". The index, derived from 10 key data points each month, captures the momentum and direction of surprises - whether positive or negative. Tested all the way back to 2005, the index has a 0.84 contemporaneous correlation coefficient with real gross domestic product growth and a 0.75 correlation to GDP with a three-month lead. Intriguingly, given that the mainland has just chalked up its slowest growth in 24 years, the surprise index is pointing upwards.