I've come across some papers in where certain forecast errors are standardized to have unit variance. Unfortunately that's the only information they provide and I have no idea on how to obtain/calculate their results.
Assuming I have a vector of 3 year forecasts that i would like to standardized to have unit variance. I thus calculate the forecast errors such as actual value-forecasted value and get a vector of forecast errors.
I've came up with the following: $x$ equals my forecast errors of the 3 year forecasts
is this correct or would this only be valid for one year forecasts?