We use the US data gathered by Reinhart and Rogoff (2010) to assess whether debt affects economic growth differently at different phases of the business cycle. In order to do that, we extend the threshold regression model of Chudik et al. (2017) and propose a new threshold quantile ARDL regression model. Our results show that to stimulate growth policy makers can manage the debt/GDP percentage according to how well the economy is doing. The estimated quantile thresholds (range 31–53 per cent) are larger than the one found by Lee et al. (2017) using median regressions, but still (much) smaller than the 90 per cent of Reinhart and Rogoff. In particular, when the US economy observes growth rates above their median value, that is when a smaller debt-to-GDP threshold affects the performance of the economy. In a steady-state situation, in general, regardless of the position of the business cycle and whether the debt-to-GDP ratio is below or above its threshold effect, less debt as a percentage of GDP boosts the US growth. Remarkably, this effect was always greater before than after World War II. Moreover, the most recent decades have witnessed the negative (positive) effect of more (less) debt when the economy had growth rates at their first quartile (median and third quartile). That is, the US policy makers are advised to reduce the debt-to-GDP ratio during expansions to promote growth.

我们使用Reinhart和Rogoff（2010）收集的美国数据来评估债务在商业周期的不同阶段是否对经济增长产生不同的影响。为此，我们扩展了Chudik等人的阈值回归模型。（2017）并提出了新的阈值分位数ARDL回归模型。我们的结果表明，为刺激增长，决策者可以根据经济状况来管理债务/ GDP百分比。估计的分位数阈值（范围在31％到53％之间）大于Lee等人发现的阈值。（2017年）使用中位数回归，但仍然（远远）小于Reinhart和Rogoff的90％。特别是，当美国经济的增长率超过其中值时，即当债务/ GDP阈值较小时，会影响经济表现。通常，在稳定状态下，无论商业周期的状况如何，以及债务与GDP的比率是低于还是高于其阈值效应，减少债务占GDP的比重都会促进美国的增长。值得注意的是，这种影响总是比第二次世界大战之后更大。此外，最近几十年见证了当经济的第一个四分位数（中位数和第三个四分位数）具有增长率时，更多（更少）债务产生的负面（正面）影响。也就是说，建议美国决策者在扩张过程中降低债务与GDP的比率，以促进增长。在最近几十年中，当经济的第一个四分位数（中位数和第三个四分位数）具有增长率时，债务增加（减少）的负面（正面）影响。也就是说，建议美国决策者在扩张过程中降低债务与GDP的比率，以促进增长。在最近几十年中，当经济的第一个四分位数（中位数和第三个四分位数）具有增长率时，债务增加（减少）的负面（正面）影响。也就是说，建议美国决策者在扩张过程中降低债务与GDP的比率，以促进增长。