Technical Supplement to "Polarization Transfer Observables in Elastic Electron-Proton Scattering at Q${}^2$ = 2.5, 5.2, 6.8, and 8.5 GeV${}^2$"

The GEp-III and GEp-2$\gamma$ experiments, carried out in Jefferson Lab’s Hall C from 2007-2008, consisted of measurements of polarization transfer in elastic electron-proton scattering at momentum transfers of $Q^2 = 2.5, 5.2, 6.8,$and$8.54$GeV$^2$. These measurements were carried out to improve knowledge of the proton electromagnetic form factor ratio $R = \mu_p G_E^p/G_M^p$atlargevaluesof$Q^2$ and to search for effects beyond the Born approximation in polarization transfer observables at $Q^2=2.5$ GeV${}^2$. The final results of both experiments were reported in a recent archival publication. A full reanalysis of the data from both experiments was carried out in order to reduce the systematic and, for the GEp-2$\gamma$ experiment, statistical uncertainties. This technical note provides additional details of the final analysis omitted from the main publication, including the final evaluation of the systematic uncertainties.