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About MDCB

    Data and Method Quality Objectives

Data Quality Objectives (DQOs) and Measurement Quality Objectives (MQOs) are or should be the foundation of all monitoring studies as these define the objectives for the monitoring and the data quality needed to respond to those objectives. MQOs are statements that contain specific units of measure such as percent recovery, percent relative standard deviation, standard deviation of X micrograms per liter, or detection level of Y parts per billion. They should be thoroughly specified to allow specific comparisons of data to an MQO. DQOs are statements that define the confidence required in conclusions drawn from data produced by a project.

The MDCB will be compiling relevant information produced by several agencies to develop clear guidance on how to define DQOs and MQOs using real-world examples from the water quality monitoring field. An expert system is being developed to connect the DQO/MQO concept to other Board products (NEMI, WQDEs).




EMMA Expert System

EPA's Quality System

Links to more DQO information - (external website)


"DQO-PRO" is a series of programs with a user interface like a common calculator and it is accessed using Microsoft Windows. DQO-PRO provides answers for three objectives:
  1. Determining the rate at which an event occurs,
  2. Determining an estimate of an averge within a tolerable error, and
  3. Determining the sampling grid necessary to detect "hot spots".

DQO-PRO facilitates understanding the significance of DQOs by showing the relationships between numbers of samples and DQO parameters such as (1) confidence levels versus numbers of false positive or negative conclusions; (2) tolerable error versus analyte concentration, standard deviation, etc., and (3) confidence levels versus sampling area grid size. The user has only to type in his or her requirements and the calculator instantly provides the answers.

For example, if you provide numbers of samples that you have (or plan to take), the calculator estimates various confidence levels or, if you provide confidence levels (as part of your DQOs), the calculator estimates the numbers of samples you'll need to obtain those confidence levels.
Switching between numbers of samples and DQO parameters such as confidence levels, standard deviations, tolerable errors, etc. is accomplished by simply leaving blank the parameter to be calculated or by selecting a button on the calculator.

EMMA is an expert system (interactive software) for project managers, administrators, and others who use or procure laboratory services for environmental analyses. It is used to plan improved and cost-effective environmental monitoring projects. It is also a highly effective teaching aid for instructors and students and was funded in part by the National Science Foundation (NSF). EMMA's new innovative technology leads you through complex decisions to tailor your plans to meet specific project needs by considering the physical and chemical characteristics of the sampling site and target analytes, desired data quality, available budget, your objectives, and the consequences of making incorrect decisions based on the data you will obtain.

EPA uses its Quality System to manage the quality of its environmental data collection, generation, and use. The primary goal of the EPA Quality System is to ensure that its environmental data are of sufficient quantity and quality to support the data's intended use. The EPA Quality System requires that each EPA Office, Region, and Research and Development Laboratory or Center develop and implement supporting Quality Systems. EPA's Quality System specifications may also apply to extramural agreement holders (i.e., contractors, grantees, and other recipients of financial assistance from EPA). The Office of Environmental Information's Quality Staff develops Agency-wide Quality System policies, develops supporting guidance and tools, provides related training and outreach, and oversees the implementation by EPA organizations. The Quality Staff may be contacted by phone at (202) 564-6830, FAX at (202) 565-2441, or E-mail at
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Last Update: September 15, 2004