Are Net Discount Rates Stationary?: Some Further Evidence
回应Gamber和Sorensen关于净贴现率均值在1977-1981年间发生水平位移的观点，通过Phillips-Perron检验和Stock-Watson q检验证明该序列是平稳的，均值恒定，且1989-1993年数据显示其正在回归均值。
Gamber and Sorensen provide evidence suggesting that the net discount ratio experienced a level shift in the mean between 1977 and 1981.If such a shift occurred, the nonlinearity in the data shows up as a failure to reject the null hypothesis that a unit root is present; that is, the series is I(1).In this reply, evidence is presented-the Phillips-Perron test and a univariate version of the Stock-Watson q-test-suggesting that the net discount ratio is stationary.Hence, the mean is constant.In addition, if one extends the analysis to include the 1989 through 1993 period, the net discount ratio appears to be reverting.