We propose a monitoring indicator of the normality of the output of a
gravitational wave detector. This indicator is based on the estimation of the
kurtosis (i.e., the 4th order statistical moment normalized by the variance
squared) of the data selected in a time sliding window. We show how a low cost
(because recursive) implementation of such estimation is possible and we
illustrate the validity of the presented approach with a few examples using
simulated random noises.Comment: 4 pages, 3 figures. In the Proceedings of the 3rd workshop on Physics
in Signal and Image Processing (Grenoble), 200
