Quality Assurance Tool
What is QAT?
QAT is the Quality Assurance Tool developed to improve the automated data integrity checks used by the Chesapeake Bay Program Office (CBPO) and to reduce the processing needed to put water quality data into the CBPO water quality database. Versions of QAT are being used by Old Dominion University, the Maryland Department of Natural Resources and the Susquehanna River Basin Commission to ensure data quality before it is submitted to the Chesapeake Bay Program Office.
What are the benefits of using QAT?
- Identifies errors within a SAS data set or text file through quality assurance checks
- Creates an output file containing all of the errors in the SAS data set or text file
- Allows for easy error correction within the SAS data set or text file
- Exports the data set to a file for easy upload to a database
How does QAT work?
QAT is an MS ACCESS database application driven by forms. The quality assurance checks are performed through a series of queries. These queries compare information in each record with look up tables (i.e., tables that define parameters, stations, and codes used for cloud cover, methods, historical ranges, etc) and with other related records. An output file is created listing all of the errors in the data set. Then, forms display errors in the data to be fixed before the data is loaded into the water quality database.
What are the quality assurance checks used by QAT?
QAT uses four types of quality assurance checks which:
- Enforce referential integrity (stations or other codes in the data set must be defined in the database).
- Identify records that has a value below the 5th and above the 95th percentile of historical data for that station, parameter, depth, and time period.
- Identify records where a part exceeds a whole (dissolved nitrogen should not be greater than total nitrogen).
- Display data in graphical formats to aid visual inspection.
Why is quality assurance important?
Data of known quality is the foundation for information registered with the Chesapeake Information Management System (CIMS) and is a necessary component of sound analysis and environmental management.
Instructions for Downloading QAT (PDF)
QAT DEMO (EXE)
For more information contact Mark Lane at lane.mark@epa.gov
