I've got say 5 million observations of weights of patients over the course of a year. Some patients have one measurement during that year and others have 30-40 (or more). I've noticed a great deal of variability. For example, on one day a patient will have a recorded weight of 120 lbs and the next a recorded weight of 220 pounds - obviously, one of those is incorrect.

In this data set, we also have the locations that are entering the weights, so it would be helpful to know which of the locations are entering the inaccurate data.

Eventually, we'd like to use this weight data in various studies but would first like to get an idea of how often these bogus weights appear in this collection.

Any suggestions?

Thanks for your help!