ABSTRACT
This chapter will discuss reference methods, procedures, and standards against which all field measurements must be compared. The validity of any measurement will depend on the accuracy of the method, procedure, technique, and instrumentation used to make it. Factors such as the precision, accuracy, and/or repeatability of any analytical effort completed outside of the laboratory can be and frequently are called into question. The individual who has made a challenged measurement in the field or in the lab must be able to document the relationship between the result he or she has reported and an appropriate, accepted, and well-established standard.
