The standard deviation of the error term in the <a href="search.pl?p=fit">fit</a> of a model to the <a href="search.pl?p=calibration data">calibration data</a>. This is a poor measure for comparing the <a href="search.pl?p=predictive validity">predictive validity</a> of time-series models; use it only if no other measures can be obtained and use it with skepticism.<o:p></o:p></P>