  Asymmetry measurements are common in collider experiments and can sensitively
probe particle properties. Typically, data can only be measured in a finite
region covered by the detector, so an extrapolation from the visible asymmetry
to the inclusive asymmetry is necessary. Often a constant multiplicative factor
is more than adequate for the extrapolation and this factor can be readily
determined using simulation methods. However, there is a potential, avoidable
pitfall involved in the determination of this factor when the asymmetry in the
simulated data sample is small. We find that to obtain a reliable estimate of
the extrapolation factor, the number of simulated events required rises as the
inverse square of the simulated asymmetry; this can mean that an unexpectedly
large sample size is required when determining its value.
