Potential GDP Level and Growth
Economic researchers often implicitly assume that the potential rate of growth of
GDP is simply the (usually non-stochastic) rate of change of potential GDP. This
assumption may turn out to be too restrictive in the case of countries that undergo
changes in economic conditions over time, which affect not only the level of potential
GDP in any given year, but also the underlying rate of growth of potential GDP (the
potential rate of GDP growth). To give empirical content to this distinction, we need a
methodology that allows us to estimate the underlying rate of growth of GDP, explicitly
disentangling it from estimated potential GDP level.
Moreover, it is often the case that researchers, in trying to estimate business
cycles, apply one or another smoothing or filtering technique to the relevant GDP series,
thus obtaining the "trend" component of the series. Researchers often calculate the
"cyclical component" as the deviation between observed and estimated trend series. The
cyclical component, however, is rarely explicitly modeled and often what researchers
have treated as the "cycle" is at best, the sum of a cyclical component plus other
components of the series.2 At worst, it may be argued that such "deviations" from trend
lack a consistent economic or statistical interpretation.
In this paper, we seek to address these two challenges simultaneously. Firstly, we
seek to disentangle the process of estimating the level of potential GDP from that of
estimating the potential rate of growth of GDP. Secondly, we explicitly model the
cyclical component of the time series under consideration. This is achieved by using
structural (unobserved components) time series models, which afford the requisite
modeling flexibility. 3 We find that in the case of Venezuela, a trigonometric cyclical
component is well-defined and has features with an interesting economic interpretation,
illustrating the nature of the association between oil prices and economic activity in that