Scale of Variation

Here we are considering both spatial and temporal scale. That is, consideration is given to the scale at which components of variation, or processes, are occurring. We decompose the noise, $e_{it}$, into:

$$e_{it}=l_{it}+q_{it}$$ (2)

where $l_{it}$ is the non-stationary deterministic mean structure or large-scale variation (spatially and temporally), and $q_{it}$ is the stationary short-scale stochastic variation.