Data Quality Control (QC) is like cleaning the toilet. Everyone wants to use a clean toilet but no one likes to clean it! The reason is simple. Like the sign in a shared toilet, “clean after yourself for next guest”, it would involve minimal work if everyone did their share of work in the first place (including sensors). But that is not the case as not everyone does it. Imagine a rig supervisor finishing his/her shift and wanting to crash in bed for a deserved rest, and then finding the Daily Drilling Report system does not allow him/her to save the data from the last 12 hours because the “bit wear code” is not valid !?! This infuriates the user and understandably may force them to ditch the application altogether. In cases like this most manual data entry applications relax many constraints during the data input process in the name of “user-friendliness”. If it is not required, then the user may never enter it. Once the missing data is not saved to the database, it goes undetected, until a few years later when someone wants to perform a study on how bits were worn out while drilling some particular formations. A quick search in the database finds nothing, even though the data entry application has a field to enter this data. After the frustration has subsided, it becomes clear that this data can never be recovered. Bummer!