FIGURE 4 

Performance of predicted head–tail interactions for PKSs. Left panel: Sensitivities and positive predictive values of the predictions for all PKSs in the data set of Thattai et al (2007). The performance of our model in which P(D|a, T) is averaged over all dependence trees is shown in red. The blue curve shows the performance if only the class information of heads and tails is used (see Materials and methods) and the green line shows the performance of random predictions. All pairs of curves show estimated PPVone standard error. Right panel: Same as the left panel, but predictions restricted to the H1–T1 subclass.