“…However, systems of SDE based models consisting of time-varying covariates seem to be rare in the statistical literature, in spite of their importance, and their asymptotic properties are hitherto unexplored. Indeed, although asymptotic inference in single, fixed effects SDE models without covariates has been considered in the literature as time tends to infinity (see, for example, Bishwal (2008)), asymptotic theory in systems of SDE models is rare, and so far only random effects SDE systems without covariates have been considered, as n, the number of subjects (equivalently, the number of SDEs in the system), tends to infinity (Delattre et al (2013), Maitra and Bhattacharya (2016c), Maitra and Bhattacharya (2015)). Such models are of the following form: dX i (t) = b(X i (t), φ i )dt + σ(X i (t))dW i (t), with X i (0) = x i , i = 1, .…”