The fundamental idea that underlies this work is that DFT may indeed be subject to proportional error, and this idea has implications wherever DFT data is fit to experiment. For example, in DFT+U, the Hubbard U values are generally fit to experimental band gaps and formation energies. Pseudopotentials also often include a fit to experimental energies. In both cases, proportional errors are usually ignored in the fit. If proportional errors, not just additive errors, were modeled while fitting Hubbard U values or pseudopotentials, one would arrive at a different and perhaps better fit. More broadly, for anyone using experimental data to calibrate DFT data, it may be useful to consider the presence of proportional errors. This idea leaves room for a wide variety of future work.