tokens: examined in this study. The positions and colors are exactly as in Figure 2 . 5. DISCUSSION AND CONCLUSIONS Examining the most extreme deviations of the posterior area distributions, we find that there is only modest improvement in our ability to measure the intrinsic parameters when using the posterior area as our metric. Neither one nor two dimensional confidence region size were significantly affected by fixing the various orientation and distance parameters. There may be some additional precision obtained in the primary spin (most notably the primary spin magnitude), however, this requires knowledge of both the sky location and either the distance or relative inclination of the system. This is likely due to a strong correlation between and the depth of the waveform amplitude modulation observed from a precessing system which is, in turn, dependent on both the spin magnitude and tilt. Qualitatively, IMRPhenomPv2 and SpinTaylorT4 exhibit similar cumulative distributions for the same event set. It is notable, but not definitive, that the improvements in region size occur at absolute region sizes. For instance, the primary tilt angle is measured better with SpinTaylorT4 , but only when the region is already relatively well contained within less than a quarter of the prior area. Conversely, IMRPhenomPv2 performs better over a wider set of regions. The deviations, while marginal, do occur for slightly different combinations of fixed parameters between the two families which may indicate that information from the merger and ringdown have some effect on our ability to measure certain parameters (e.g., spin orientation and magnitude). This result reinforces the generally known result that the intrinsic source physical parameters and the source orientation parameters are mostly decoupled. Even in the case of precessing binaries where the spins and inclination are correlated because of the oscillation of the binary plane, we find here that having information about the inclination of the binary does not translate into noticeably better estimation of the spin parameters. Moreover, this result represents the best possible scenario in regards to incorporating priors from external astronomical information—it effectively introduces a prior which is a delta function. In practice, the prior information will have a finite width and many gains made here will likely be lost. Finally, we do note that, while not explored in detail here, the overall run times of the codes are reduced when fixing parameters. The effective decrease in dimensionality will improve convergence time in the MCMC used for measurement of the posteriors. Empirically, IMRPhenomPv2 was reduced by a factor of two between the unpinned case and the case fixing only sky location. Other configurations converged only slightly faster than the sky location case. The SpinTaylorT4 family configurations were affected in a similar way, but we observed a little less than a factor of two. For most compact
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