Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
This paper extends the asymptotic theory for the fractional Vasicek model developed in Xiao and Yu (2018) from the case where H∈(1∕2,1) to where H∈(0,1∕2). It is found that the asymptotic theory of the persistence parameter (κ) critically depends on the sign of κ . Moreover, if κ>0, the asymptotic distribution for the estimator of κ is different when H∈(0,1∕2) from that when H∈(1∕2,1).