Receiver operating characteristic of test alignments. False positive rates of RNAz-positive test alignments versus true positive rates at different cutoff levels c. The left plot depicts rates in case undecided alignments are included in the calculation. Meaning that the true positive rate is defined as , where tp denotes alignments which have been correctly classified to contain the ncRNA in the same reading direction as the input alignment. fn is the number of alignments which have been falsely classified to contain the ncRNA on the reverse complement, while u contains all alignments which contain the ncRNA in the same reading direction but RNAstrand were not able to predict a reading direction. False positive rate is defined respectively. The right handed plot discards unclassified alignments. Hence, the true positive rate is defined as and the false positive rate as . The curves for both SVM decision classes are given. Red curves denote alignments containing the ncRNA in the reading direction of the input alignment. Black curves belong to alignments which contain the ncRNA on the reverse complementary strand. The values of c range from 0 to 0.95 in steps of 0.05.