In order to analyze how bit collisions affect the prediction of mass spectra, a simple drop-bit-collision model was examined. The drop-bit-collision model is trained on the NIST library excluding compounds where bit collision occurs against target compounds. Since we dropped the compounds only considering bit collisions, the performance is sensitive to targets: For T-3, the similarity and rank worsen in comparison with NEIMS and our model, whereas the highest similarity and rank is confirmed for the T-4 compound. On average, similarities and ranks are reasonable. The overall trend indicates that the MSS undersampling designed to train from the training data suitable for specific targets, performs reasonably for all the targets.