Function to evaluate the simulation performance with regard to bias using the median relative error (MRE) and precision using the coefficient of variation.
Note
Compares against operating_mod only, so it is valid when the
replicates redrew the observations alone. If they were produced with
sim_mod(process = ) / self_test(process = ), the operating
model's deviations are no longer what generated the data and the bias this
reports is an artefact. Compare against
attr(sims, "process_sim") in that case. Passing a
self_test result that holds process draws warns, since the
attribute makes that case detectable rather than only documented.