Mean squared error seems pretty principled. Normalizing by variance to make it more comparable to other distributions seems pretty principled.
I guess after that it seems more natural to take the standard deviation (to get RMSE normalized by standard deviation), than to subtract it off of 1. But I guess the latter is a simple enough transformation and makes it comparable to the (more well-motivated) R^2 for linear models, so therefore more commonly reported than RMSE/STD.
Anyway, spearman r is −0.903 (square 0.82) and −0.710, (square 0.5) so basically the same.
Hm.
R² = 1 − (mean squared errors / variance)
Mean squared error seems pretty principled. Normalizing by variance to make it more comparable to other distributions seems pretty principled.
I guess after that it seems more natural to take the standard deviation (to get RMSE normalized by standard deviation), than to subtract it off of 1. But I guess the latter is a simple enough transformation and makes it comparable to the (more well-motivated) R^2 for linear models, so therefore more commonly reported than RMSE/STD.
Anyway, spearman r is −0.903 (square 0.82) and −0.710, (square 0.5) so basically the same.