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Clean Air Markets

Eliminating Bias

The Acid Rain Program experience has shown that continuous emissions monitor (CEMS) operators can eliminate bias from monitoring systems by instituting appropriate installation, operation, and quality assurance procedures. The “An Operator’s Guide to Eliminating Bias in CEM Systems” on this page provides information recognizing the physical and operational problems that produce systematic error and their available remedies.

The Guide makes it easier for CEMS operators to improve a monitor's accuracy and meet regulatory requirements. We recommend viewing the entire individual chapters.

The Guide is organized into eight chapters:
  • Chapter 1 describes the history and the engineering and statistical basis for the bias test.
  • Chapters 2 through 7 describe problems that can cause systematic measurement error and remedies that can be taken to address those problems. Each chapter includes a table summarizing the problems discussed in that chapter.
    • The Checklist provides a cross-reference of all the problems discussed in these chapters.
  • Chapter 8 discusses elements that should be incorporated into ongoing quality assurance programs to detect and prevent the problems that produce systematic error in monitor measurements.

For more emissions monitoring resources, return to Emissions Monitoring and Reporting.

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