Friedman's Plucking Model of Business Fluctuations: Tests and Estimates of Permanent and Transitory Components
构建了一个正式计量模型，将弗里德曼的“拔毛”假说（产出受上限约束、衰退时被向下拉低）与随机趋势周围的非对称波动结合起来，并允许异方差和增长率冲击，为衰退的暂时性和持续时间依赖性提供检验。
More than thirty years ago Milton Friedman proposed a 'plucking' model of business fluctuations in which output cannot exceed a ceiling level, but will, from time to time, be plucked downward by recession. The model implied that business fluctuations are asymmetric, that recessions have only a temporary effect on output, and that recessions are duration dependent while expansions are not. Subsequent literature has provided copious empirical support for these propositions, but econometric models of business fluctuations have not incorporated these features. This paper presents a formal econometric model which encompasses both plucking and asymmetric fluctuations around a stochatic trend while allowing for heteroskedasticity and shocks to the growth rate.