Abstract: A method for determining statistical characteristics of a measurable property includes the initial step of monitoring the property and generating an electrical signal, the magnitude of which is a representative measure of the property. The electrical signal is passed through a high pass filter to eliminate low frequency noise which would otherwise tend to affect artificially extreme values of the signal. The maxima of the filtered signal is then determined within defined time intervals and extreme value statistical analysis is applied to the maxima of the filtered electrical signal to determine statistical characteristics of the measurable property. This method and apparatus for performing the method may be favorably applied to monitoring weight basis of sheet material, such as paper, as the material is being produced.