For the other mass tolerances, similar FD rates were found except for the 0.001 Da mass tolerance. Figure shows that, if the mass window is set to 0.001 Da, the FDr increases to 49.1% at a score CN L threshold of -0.95. In general, a higher FDr was found for the real samples compared to the database fragments as well as a lower overall reduction rate of 7.2%. While the total number of evaluated cases, 5526, is significantly lower than the almost 5 million cases for the database fragments, a similar 1:1 ratio of correct and wrong fragment cases was observed.