What is the normalized RMS?
This quantity is also known as the reference standard deviation (the square root of the reference variance), the standard deviation of the observation of unit weight, and other names. It is a unitless quantity, and its expected value is 1.0. Values of the normalized RMS greater than 1.0 mean that the weights assigned to some or all of the observations were too large. This can happen if the user’s data set or one or more of the reference stations contains particularly noisy data. Most runs of OPUS-RS produce a normalized RMS of 1.0 or less, meaning that the noise in the data was actually less than would be indicated by the assigned weights.
