The independent Office for Budget Responsibility on Tuesday said it has overestimated the strength of economic growth over the last two years. The OBR said in its forecast evaluation report that spending reduction together with tax increases might have hurt the economy more than initially estimated. "While the discretionary tightening in fiscal policy has arguably been a little smaller than planned in the Coalition's first Budget, it could have acted as a bigger drag on growth than we expected," it said. The OBR is slated to publish economic forecasts on December 5 for Chancellor's autumn statement. According to OBR, some of the weakness of productivity relative to the pre-crisis trend is likely to be a temporary phenomenon. But it assumes that a significant proportion of the hit is likely to be permanent or long-lasting.