MS-QA_06-2019 rev5

MS-QA 2019 3 Companion Guidance Section C—Understanding Statistical Counting Errors (CRM) MS-QA Companion Guidance Section C Understanding Statistical Counting Errors for Various CRM Instruments Relative to Detector Sensitivity for Counts Per Hour (cph) The below table illustrates uncertainty in statistical counting (inherent to all detector designs) that varies with different commonly used models of Continuous Radon Monitors (CRM) and Electronic Integrating Devices (EID). Uncertainty regarding statistical counting for different detector sensitivities (in terms of counts per hour) is illustrated for various time periods of exposure relative to different radon concentrations. This information can aid understanding the trustworthiness of an hourly reading (and the average for a group of hourly readings) relative to the radon concentration being measured. Key ( potential counting error) Red is ≥ 14% Orange is ≥ 10% Light orange is ≥ 6% Yellow is less than 6% Detector Sensitivity Detector Sensitivity Detector Sensitivity Advisory These values do not intend to represent that test results across any specific time duration will exhibit error exactly as shown, nor do they represent all potential errors and confounding factors.