McCallum claims that the statistical evidence provided by Nelson and Plosser cannot be interpreted as providing support for RBC theory, since this evidence is equally consistent with other theories of the business cycle. In short, West builds a simple model with overlapping wage contracts in which monetary policy is the only source of disturbances. The first piece of evidence is that the sample autocorrelations for annual GNP data are large and decay slowly. The argument is completed by the idea that monetary shocks are necessarily temporary and so can only affect the cyclical component, and that the long run path of the economy is mainly guided by real factors such as tastes and technology. Trend Stationary: A time series that does not exhibit a trend. There are some finer-grained notions of stationarity that you may come across if you dive deeper into this topic.
They try to answer this question by using the two measures of persistence discussed before: the ones by Campbell and Mankiw and Cochrane For each data set, single-country ADF tests are also conducted. In other words, the existence of unit roots leads to the inference that movements in output are persistent.
Despite the arguments that the use of panel data increases the power of unit root tests, this methodology also has some problems and limitations. This paper intended to explore some of these controversies, assessing some aspects of the unit root literature in econometrics and macroeconomics. Moreover, if the idea of near random walk is a valid description of the behavior of GNP or, in other words, if GNP is trend reverting but with a high degree of persistence, it seems that the concept of a unique and stable natural rate is not very useful anyway.
Nelson and Plosser's main conclusion in terms of macroeconomic theorizing follows directly from such reasoning, and can be summarized as: We conclude that macroeconomic models that focus on monetary disturbances as a source of purely transitory stationary fluctuations may never be successful in explaining a very large fraction of output fluctuations and that stochastic variation due to real factors is an essential element of any model of economic fluctuations. In sum, a quick review of the literature of unit roots in Latin American countries shows no conclusive result, which is also consistent with the literature on developed countries. According to Campbell and Mankiw , traditional theories of economic fluctuations accept two basic premises: i.
The four panel data unit root tests applied by Rapach seem to confirm the inferences drawn from single-country tests: the null of unit roots is rarely rejected in these tests. Perron's work has received some criticism in the literature, based on the fact that the breaking point is exogenously selected. Possibly, some sort of equilibrium rate of output would need to be assumed in the long run, even if the process of return to trend is assumed to be very slow due to rigidities and other forms of imperfections like in many models in the new Keynesian literature. However, their results for some of the series industrial production, nominal GNP, and real GNP reinforce Perron's conclusions against the unit root hypothesis, which is rejected even after endogenizing the breakpoint selection.
Besides, he points out that the tests performed by Nelson and Plosser have low power not against TS models with an AR root close to unity but, more importantly, against plausible TS models estimated from the data. In his paper, however, the evidence suggests the opposite result of the previous two studies. The paper by Noriega and Ramirez-Zamora presents many similarities with the work of Utrera undated mentioned before. On the other hand, it is also possible to make a case against sharp contractions as a response to financial or currency crises Dutt and Ros, , since the negative effects of such policies do not tend to dissipate in the short run.
They are: They are: Stationary Process: A process that generates a stationary series of observations. But conventional atheoretical measures of persistence convey little information about this question, and structural inferences based on such measures ought to be viewed with extreme skepticism Christiano and Eichenbaum, , p. In addition, concerning the stationarity of the cyclical component, Nelson and Plosser admit it is a proposition that cannot be inferred from empirical analysis.
The empirical literature on the existence of unit roots in GNP time series is enormous but concentrates mainly on developed countries, with the US coming at the top of the rank. Utrera undated concludes that GDP in Argentina is better described as a stationary variable. It is clear that West minimizes the importance of unit roots in GNP series, based on the fact that random walk and near random walk behavior cannot be distinguished.
Their basic proposition is that it is not possible to provide a compelling case that real GNP is either trend or difference stationary based on the analysis of postwar data. In some cases, the very concept of a unique long-term trend of output is abandoned. Also in this case, McCallum argues, the evidence is far from conclusive, since unit root tests have low power to distinguish between a DS process and a TS process with an AR root close to unity. In the second paper, Cribari Neto expands the sample for the period and, using the same methodology, confirms the results of his study.