Submitted by ASA-ENVR for competition
Session Slot: Sunday, 4:00-5:50
Estimated Audience Size: 50-60
AudioVisual Request: overhead and slide projectors
Panel Session Title: How Low Can We Measure: The Statistics of Detection
and Quantitation
Theme Session: Yes
Applied Session: Yes
Session Organizer: Coleman, David Alcoa
Address: Applied Math & Computer Tech. (483), ATC-D-10 Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069
Phone: 724-337-5913
Fax:
Email: david.coleman@alcoa.com
Session Timing: 110 minutes total (Sorry about format):
Opening Remarks by Chair - 5 minutes Panelists Comments/Discussion - 85 minutes Floor Discussion - 20 minutes
Abstract: A multitude of statistical issues surrounds the seemingly simple question: ``How low a concentration or level can we reliably measure or detect?'' This question is pertinent to environmental sciences and analytical chemistry, but also to medical sciences and national defense. In this session, four distinguished panelists with diverse background present and tackle some of these issues, then discuss and debate the merits of various solutions. One concern is how to balance detection sensitivity with false positives/false alarms. Also important is selecting a population subsample; estimating between-lab and within-lab sources of bias and variation; developing calibration methods that will work in the face of heteroscedasticity and the presence of outliers; describing the relation between measurement uncertainty and significant digits; and applying equivalence testing.The first panelist will comment on the statistical and conceptual properties of various estimators for the quantification limit and address issues of bias, variability and robustness. The second panelist will describe the calculation of detection limits for ion-chromatographic data and discuss the strength and weaknesses of two approaches. The third panelist will comment on the application of statistical models to accommodate heteroscedasticity and traditional laboratory approaches for estimating detection limits. The fourth panelist will describe the newly adopted ASTM standard practice for detection and the proposed standard practice for quantification.
This session addresses the theme of statistics as a guide for policy.
Everyone has or should have an interest in how low a concentration -
such as lead in water, PCB's in soil, carbon monoxide in air - can reliably
be measured. The requirement to protect human health and ecosystems
has caused regulatory agencies to push for lower limits on pollutants,
but the ideal 0% is unattainable; so policy must be established to
determine acceptably low limits. That policy should be based on
statistics, analytical chemistry, and practical considerations.
This session will be of interest to applied statisticians. Because all measurements are uncertain, statistics and analytical chemistry must be used jointly to estimate the lowest concentration that can be reliably detected and the lowest concentration at which one can reliably report a numerical measurement value. Issues at hand that will be discussed and are of interest to applied statisticians are selection of sample population, biases (e.g., between labs), heteroscedasticity, blind trials, false detections, power of detection, significant digits, and calibration.
This session will be of interest to members of other ASA sections including
the Sections on Physical & Engineering Sciences, Government Statistics,
Biometrics, and Health Policy. Statisticians, environmental
scientists, and policy-makers in government regulatory agencies, USGS,
DoD, and NIST will be interested in this topic.
Session Chair: Wendelberger, Joanne R. Los Alamos National Laboratory
Address: Los Alamos, NM 87545
Phone: 505-665-4840
Fax: 505-667-4470
Email: joanne@lanl.gov
Gibbons, Robert University of Illinois
Address: Chicago, IL
Phone: 312-413-7755
Fax: 312-996-2113
Email: robert.gibbons@uic.edu
Address: Dallas, TX
Phone: 972-995-7541
Fax:
Email: ALAV%mimi@magic.itg.ti.com
Davis, Charles Environmetrics & Statistics Limited
Address: Envirostat, Environmetrics and Statistics Ltd., 1853 Wellington,Henderson, NV 89014
Phone: 702-456-8994
Fax: 702-456-8114
Email: bromero@compuserve.com
Address: Applied Math & Computer Tech. (483), ATC-D-10 Alcoa Technical Center, 100 Technical Drive, Alcoa Center, PA 15069
Phone: 724-337-5913
Fax: 724-337-4911
Email: david.coleman@alcoa.com
List of speakers who are nonmembers: 1 - Lynn Vanatta