| After having established the stationarity of the variables the production function was fitted. |
| To test if a variable is stationary, a formal test of stationarity called the Augmented Dickey-Fuller test is commonly used. |
| The ADF, DF-GLS and NP test the null of unit root whereas the KPSS tests the null of stationarity. |
| A stationarity requirement, defined as a constant mean, variance and autocorrelation through time, constrains parameters to a certain range. |
| Given the nature of time-series data, it is necessary to test the stationarity of each individual series. |
| The composition stationarity test using the hymenopteran data was designed in a similar way, using just the 16S gene. |
