D ata Q u ality

D a ta Q ua lity M a trix

D eterm ining the level of accuracy and precision desired at the project’s beginning is im portant. T able 4-1 has been developed to help determ ine the data quality objectives. T he table identifies three data quality levels for six com m only collected w ater quality param eters. T he purpose of the w ater quality data m atrix is to help collectors select the level of data quality that m eets their objectives, experience, level of expertise, and budget. D ata quality levels depend on the m ethods used and the Q A /Q C protocol follow ed.

L evel A L evel A is the highest level of data quality. It can

be used to assess com pliance w ith w ater quality standards, perm itting requirem ents, or other regulatory activities.

L evel B L evel B is the next highest level. It is typically easier and less expensive to collect. L evel B data can be used as an early w arning of potential problem s or for screening inform ation.

L evel C L evel C is the low est data quality level and is norm ally the easiest to collect. B ecause of its low er accuracy and precision, L evel C data is best used for educational purposes.

N ot all field param eters w ill need to be at L evel A , or even L evel B , data quality. A principal decision for data collectors is to decide how the data w ill be used.

D epending on the data collection objectives, equipm ent available, collector training and adherence to Q A /Q C procedures, data quality levels m ay vary for different param eters. T he procedures and instrum ents described in the D epending on the data collection objectives, equipm ent available, collector training and adherence to Q A /Q C procedures, data quality levels m ay vary for different param eters. T he procedures and instrum ents described in the

R eferences

U SE PA . 1996. The volunteer m onitor’ s guide to q u a lity a ssu ra n ce p ro ject p la n s.

E PA 841-B -96-

003. U .S. E nvironm ental Protection A gency, O ffice of W etlands, O ceans, and W atersheds: W ashington, D .C . C hapter 2.

T able 4-1. W ater quality param eters by data quality level. D ata quality level depends on a com bination of quality control and m ethod selection.

D A T A Q U A L IT Y M A T R IX W ater Q uality P aram eters by D ata Q uality L evel D ata Q uality L evel depends on a com bination of quality control and m ethod selection.

E . coli Q uality

D ata

W ater