As a second test, we return to the data presented above for F2, with the target quantities of Table . Using guided point selection converges the RMSD to 0.01 cm -1 with seven high-level points, fewer than the nine that were chosen by hand. Detailed results are shown in the Supporting Information. All the target quantities have errors less than 0.01 cm -1 . As the highlevel points are accumulated, the RMSD decreases. In this case, we have access to "correct" values and see that the RMS errors also decrease. The RMS errors of direct fitting, using eq. ( ), also decrease, although they are larger than the errors from guided fitting.