 The paper reviews and classifies statistical transformations for post-processing regional climate model, RCM, output into three categories, distribution-derived, parametric, and non-parametric transformations, each with different underlying assumptions. A real-world application using Norwegian precipitation station observations shows that non-parametric transformations have the highest skill in reducing biases in RCM precipitation. This article was authored by J. E. Haugen, T. Engenskogen, J. B. Bremmins, and others.