| A stationarity requirement, defined as a constant mean, variance and autocorrelation through time, constrains parameters to a certain range. |
| After having established the stationarity of the variables the production function was fitted. |
| The ADF, DF-GLS and NP test the null of unit root whereas the KPSS tests the null of stationarity. |
| Testing for cointegration involves testing the residuals from an OLS regression for stationarity. |
| Coefficients of the ARMA models are also checked for both stationarity and invertibility. |
| To ascertain nonstationarity or stationarity of time series variables, DF-GLS, Ng-Perron and KPSS tests are implemented. |
