# What is the RMSE normalized by the mean observed value called?

I have been using the Root Mean Squared Error (RMSE) to measure the accuracy of values predicted using a model. I understand that the value returned is using the units of my measures (rather than a percentage). However, I would like to quote my values as a percentage. The approach that I have taken is to normalize the RMSE by the mean value of my observations.

Is there a term for RMSE/mean ?

In my field (analytical chemistry), absolute error / absolute value = relative error, so relative RMSE [at mean x] would be understood easily.
• I'm not sure if there is a standard term in my field, so I will probably use relative error as it sounds a little more self-explanatory. – celenius Apr 21 '12 at 13:37