Stationary conditions of individual variables employed in this study are verified using Augmented Dickyfuller unit root test and lag order according to AIC.
Table 2 report results of log first difference stationarity tests. Results supports stationary conditions for the various variables at the stated lag order selected by AIC.
Table 3 as noted earlier presents result of Standard Vector Autoregression test based on equations (la) to (le). Results features coefficients estimates illustrating relationships between key US economic and performance indicators and modeled policy uncertainty parameter.
Using optimal lag range chosen by HQIC and AIC, (i.e. lag order between 1 and 3 according to Table 1), this study finds that policy uncertainty has direct significant impact on all performance indicators or variables tested. Policy uncertainty is found to have significant impact on unemployment rate only with optimal lag order of 1 (chosen by HQIC instead of AIC adopted in this study). Coefficients estimates reported in Table 3 show that policy uncertainty has significant negative effects on fixed private investments growth, GDP growth and prevailing interest rates. This outcome to some degree reflects present US macroeconomic trends since economic slowdown brought about by the 2008 recession. With the exception of interest rates, which has remain relatively low in post-recession US economic environment, performance of other test variables have been well below expectations; a condition which some analysts have attributed to growing policy uncertainty generated lack of predictable policies and political will to implement expected policies by stakeholders in Washington. These results, thus, suggest that deficit induced policy uncertainty has significant constraining effects on key performance indicators in the US economy.