Data quality objectives (DQO) for the project are defined in the Quality Assurance Project Plan (QAPP) that accompanies the Monitoring Plan. Each agency has established DQOs for every field and laboratory parameter it is responsible for measuring. Agency DQOs are discussed in detail in the text of the QAPP (Section 2.5), and summarized collectively in Table 3 of that document. Discussion of DQOs includes definitions for the quantitative goals of precision, accuracy and completeness, and the qualitative goals of representativeness and comparability. Not all objectives are relevant to each type of data collected by the various agencies.

The quantitative DQOs include precision, accuracy and completeness. Precision is defined as the agreement among a set of replicate measurements with no assumption that a true value is known. Accuracy is the closeness of agreement between an observed value and an accepted reference value. A stated percent of samples collected properly and analyzed acceptably constitutes a complete data set.

The qualitative DQOs include representativeness and comparability. In the discussion of representativeness of a sample site, the rationale for the sampling design is provided. Demonstration of sample representativeness involves a description of the steps by which the sample is collected. Comparability refers to the methods used to collect and analyze the sample. The Standard Operating Procedures (SOPs) should outline methods commonly used by laboratories or, if the methods are modified for the project, these changes should be documented. Finally, the results should be available to be included in an inter- or intra-laboratory data base.