  Measurement choices in weakly-measured open quantum systems can affect
quantum trajectory chaos. We consider this scenario semi-classically and show
that measurement acts as nonlinear generalized fluctuation and dissipation
forces. These can alter effective dissipation in the quantum spread variables
and hence change the dynamics, such that measurement choices on the coupled
quantum dynamics can enhance quantum effects and make the dynamics chaotic, for
example. This analysis explains the measurement-dependence of quantum chaos at
a variety of parameter settings, and in particular we demonstrate
quantitatively that the choice of monitoring scheme can be more relevant than
system scale $\beta$ in determining the `quantumness' of the system.
