Compiling a database of experimental data takes a lot of time and effort, it is a serious undertaking even for relatively large groups (like the NIST MS Datacenter team with their NIST RI and NIST MS databases). Even if some parts of the process are automated and there is a strict pipeline for checking for potential errors, some incorrect entries can get through . Most of the compounds in METLIN SMRT do not have explicit replicate retention time measurements, therefore finding potential errors by statistical methods is impossible. Manual inspection is not a viable approach either because of the database size.