And there is little to suggest that this sort  1  It could be added that taking on board some of these sorts of change may involve being prepared on occasion to give some weight to judgement before all the empirical evidence is crystal clear - while recognising that you might be wrong and trying to weigh the costs of being wrong.
A case in point would be the way US policy makers backed their judgement about higher trend productivity growth before it was all that clear in the official data. BIS Review 37/2003  1  of ongoing evolution of economic structure poses greater problems for policy makers today that it has in the past.