Recorded Radial-Velocity Adoption and the Transverse-Speed Distribution of LAMOST-Selected Metal-Poor BHB Candidates

Six-dimensional Galactic-archaeology samples add a radial-velocity (RV) requirement to an astrometric parent. We audit recorded RV adoption using Gaia transverse speeds for 206 LAMOST-selected metal-poor blue horizontal-branch (BHB) candidates. The recorded groups of 120 stars with adopted RVs and 86 without have median speeds of 67.5 and 169.3 kms−1; historical query completeness for the latter is unknown. After training-fold preprocessing and consistent observed/null scoring, tests retaining the original fixed partition give p=0.0106 and 0.0088. A fixed source-ID partition does not reject the hypothesis, while prediction gains are positive in 19 of 20 source-ID partitions. These overlapping partitions are not independent replications or a calibrated combined test; conditional association remains inconclusive. Defined DR12 parameter products change 15 availability labels; general medium-resolution products change another 15. Inverse-probability weighting provides an internal reconstruction test against the observed parent distribution. Including speed improves the two tail-fraction point estimates, but the median error increases from −1.7% to +13.6% relative to covariate-only weighting. All paired 95% intervals for improvements in absolute reconstruction error include zero. Recorded RV adoption defines groups with different observed transverse-speed distributions; the weighting exercise does not demonstrate superiority of the speed-informed model. This parent-based audit does not identify missing radial velocities or orbital distributions.