A number of separate effects contribute to the difference in H₀ inferred from WMAP-7+S12 (top of left panel) and H₀ inferred from Planck+WP (bottom of left panel), all going in the same direction. These include assumptions about neutrino masses, calibration procedures, differences between WMAP-7 and WMAP-9, and differences in the relative calibrations between SPT and WMAP (as explained in the text). The right panel shows calibration parameter priors (top lines of each pair) and posteriors (bottom lines of each pair). The tighter of the priors shown for WMAP-7+S12, and that shown for WMAP-9+S12, come from using Planck to provide the relative calibration between WMAP and S12. We plot only the posterior for the Planck+S12 relative calibration. Note that the relative-calibration parameter is between S12 and the other indicated data set (i.e., WMAP or Planck).