CHICAGO — A Measurement Quantization analysis combines four mature paired-mode gravitational measurements to assess a common difference between free-deflection and electrostatic-servo results. Recalculation from stated rounded inputs gives a servo-normalized gap of 61.0 ± 26.9 parts per million, with one standard uncertainty. The fit retains the NIST cross-configuration covariance and assumes zero additional covariance between campaigns.

The four pairs are BIPM Mark I, corrected BIPM Mark II, NIST copper and NIST sapphire. These are published experimental determinations; the synthesis and their association with MQ’s two realization regimes are subsequent MQ analyses. Both operating modes measure gravitational torque, through different readout and calibration procedures. Figure 1 separates the principal statistical comparisons.

The reproduced result is 60.9932 ± 26.9309 ppm. Its small final-digit difference from the source’s 60.994 ± 26.930 ppm summary reflects reconstruction from the explicit rounded inputs. Both give the same reported 8.14-to-1 fixed-MQ-versus-zero likelihood comparison. The freely fitted center is above MQ’s 34.9284 ppm target, although the target is within one standard uncertainty of it.

This does not distinguish MQ from a generic positive offset caused by apparatus effects. The fitted model gains a parameter; illustrative information-criterion comparisons remain modest. The source reports that an additional heterogeneity treatment reduces the fixed-target-to-zero ratio to about 5.4 to 1. That reported sensitivity is separate from the primary-budget calculation reproduced here.

The uncertainty boundary matters. The NIST inputs include published primary systematic contributions and correlations, but this fit omits the additional unidentified configuration effects used for NIST’s final consensus. Copper carries about 81.56 percent of the common fit’s linear weight, so four positive central differences must not be described as four independent strong confirmations.

Historical corrections and unfavorable results remain part of the account. An early preliminary servo problem is excluded rather than counted as another positive result. The corrected BIPM Mark II combined absolute value lies 9.14 published BIPM standard uncertainties above the current MQ upper-count value, before any unquantified model discrepancy. Agreement in mode ordering does not resolve that absolute-value tension.

The analysis identifies a focused measurement question. A prospective comparison must fix the mode assignment, normalization and uncertainty model in advance and control mode-dependent instrumental bias. The detailed Brief supplies the four input pairs, propagated contrast covariance, fit weights, exact MQ target construction and likelihood calculation. The present evidence does not identify the physical cause of the gap.

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