Abstract: (arXiv)
Time shifting the outputs of Gravitational Wave detectors operating in coincidence is a convenient way to estimate the background in a search for short duration signals. This procedure is in fact limited as increasing indefinitely the number of time shifts does not provide better estimates. We show at the contrary that the false alarm rate variance saturates with the number of time shifts. The computation is explicitly done for 2 detectors and for 3 detectors where the detection statistics relies on the logical ‘OR’ of the coincidences of the 3 couples of the network. We also investigate with different methods the effect of noise non stationarities. We find that for the case of mild non stationarities time slides larger than the non stationarity time scale can be used.