An auxiliary data is Data derived from a source other than EMAP, that is, from an experiment or from another monitoring or sampling program, either Federal or State. The sampling methods and quality assurance protocols of auxiliary data must be evaluated before the data are used. It is always important to establish the population represented by auxiliary data. (Preferred term 1993; replaces "non-EMAP data," and "found data," deleted in 1993; see related: ancillary data.)