Figure 4

Receiver operating characteristic curves 3. The receiver operating characteristic curves for the two sampling scenarios, (a) according to the mussel data and (b) according to the deteriorated sampling, with prior knowledge on the frequency of the periodicity. The methods correspond to the rank based estimator (Robustperiodic), which does not take non-uniform sampling into account, Tukey's biweight regression estimator (M-estirnator) and the Bayesian method (Bayesian) presented in [15]. The frequency at which to look for periodicity is deliberately different from the true underlying frequency by approximately 25% to observe the effects of choosing the frequency incorrectly. In both (a) and (b) the effect of 1, 2 or 3 outliers is seen by the shift towards the chance diagonal (the closed to the chance diagonal corresponding to the 3-outlier case) from the case of no outliers.