A comparison of the calibrator and Hubble-flow samples in host-galaxy morphology, host-galaxy reddening, and optical light-curve decline rate. Blue circles show the Hubble-flow sample J-band Hubble-diagram residuals (left axis), while red squares show the calibrator absolute J magnitudes (right axis). The open circles indicate three fast-declining SN Ia that are excluded from our fiducial sample as outliers. These plots are used to define sample cuts only. Distances are based on the J-band photometry alone, with no corrections from these diagnostic parameters.