In a year when a forecast for the structural budget deficit turns out to have been over-optimistic, the government can still claim that its own calculations show the shortfall to have been cyclical rather than structural. After all, estimation of potential output – and hence the cyclical versus structural decomposition of the fiscal position – is notoriously difficult, even after the fact.
而周期性地调整财政限制制度尽管在其对宏观经济的影响方面非常有利，却无助于解决财政预测偏差的问题。事实上，这只会让问题变得更严重。对结构性预算赤字的预测被证明过度乐观的一年，政府依然可以声称其内部计算显示差额的出现是周期性而非结构性的。毕竟对潜在产出的估算——从而对财政状况进行周期性或是结构性的解读——是出了名的困难，即便是在事实之后计算也是如此。