False-alarm probabilities as a function of the total number of cycles in the data set, based on Monte Carlo simulations. Upper panel: (Corrected) Original method of Gough (1981). Lower panel: modified method (Gough 1983). The red lines give the FAP that a realization of case C falls within the 99% confidence interval for case R, and vice versa for the blue lines. The dashed line segment indicates an upper limit.