Biomedical subjects

D A Chambless

Publications and source records attributed to D A Chambless.

4 recordsLinked to original sources

PubMed1995

Significant digits: foundations, myths and utilization.

Scientific text books, journal articles, and all types of other sources of scientific information frequently give certain recommendations and/or make statements of presumed fact concerning the issue of significant digits in scientific computation. Most of these "well-known" facts concerning significance in computation are false. This article discusses the folklore of significant digits, debunks the common cliches, illustrates the actual behavior of computational significance in a typical scenario, and makes recommendations concerning these matters.

Biometry↗

PubMed1994

"Exact" and approximate methods for analysis of total error in radiation measurements.

Radiation measurement results are typically stated as an estimated activity concentration with an associated 95% error bound. Very frequently, however, the error bound cited at the "95% confidence level" is nothing more than counting error and, especially at higher levels of activity, counting error may constitute a gross understatement of the total error that should reasonably be attributed to the measurement. This paper compares the measurement confidence limits obtained using a typical approximate error propagation procedure with the "exact" confidence limits. A Monte Carlo error propagation method is also considered. The results of the three methods are compared using 222Rn measurement procedures for illustrative purposes.

Monte Carlo Method↗

PubMed1992

Detection limit concepts: foundations, myths, and utilization.

Detection limit parameters such as the minimum detectable concentration have been widely discussed in the literature for more than 30 y. Misunderstanding and misapplication of these parameters continue to be widespread and, indeed, even encoded into computer programs, especially those developed in recent years for use with PC-based analyzer boards. This brief review of the principal concepts related to the most common types of detection limits provides guidance for correctly using these parameters. In particular, several myths concerning issues such as the "sample-specific minimum detectable concentration" and the "unreliability" of measurements made below this concentration are discussed.

Radiometry↗

PubMed1984

Fully automatic quantitative analysis of alpha-radiation spectral data using a minicomputer.

Fully automatic computer programs for the analysis of alpha-spectroscopy data have been developed and installed on a PDP-11/45 minicomputer at the Eastern Environmental Radiation Facility (EERF) of the U.S. Environmental Protection Agency (EPA) in Montgomery, AL. The programs presently in use evaluate the activities of the U, Pu and Am nuclides of interest to EERF. A mathematical enhancement of the spectra processed makes reliable determination of nuclide gross counts possible without the human interaction previously necessary at the laboratory. A number of safeguards that attempt to detect conditions (anomalous chemistry, etc.) which may cause invalid analyses are provided in the programs.

Alpha Particles↗