You are here:
ROLE OF LABORATORY SAMPLING DEVICES AND LABORATORY SUBSAMPLING METHODS IN OPTIMIZING REPRESENTATIVENESS STRATEGIES
Citation:
Nocerino, J M., B A. Schumacher, AND C C. Dary. ROLE OF LABORATORY SAMPLING DEVICES AND LABORATORY SUBSAMPLING METHODS IN OPTIMIZING REPRESENTATIVENESS STRATEGIES. ENVIRONMENTAL FORENSICS. Taylor & Francis, Inc., Philadelphia, PA, 6:35-44, (2005).
Impact/Purpose:
The overall objective of the chemometrics and environmetrics program and this task is to examine and evaluate the statistical procedures and methods used in the measurement or experimentation process and to improve those procedures and methods (if deemed inadequate) by investigating, developing, and evaluating statistical methods, algorithms, and software to reduce data uncertainty. The measurement or experimentation process encompasses: decision objectives and design, sampling design, sampling, experimental design, quality control, data collection, signal processing and data manipulation, data analysis, validation, and decision analysis. Other general objectives of the program are to: evaluate certain existing, developed, or potential performance measurements for information content, relevancy, and cost-effectiveness. The objectives of the sampling research area are to provide the Agency with improved state-of-the-science guidance, strategies, and techniques to more accurately and effectively collect solid particulate field and laboratory subsamples that best represent the extent and degree of contamination at a given site.
Description:
Sampling is the act of selecting items from a specified population in order to estimate the parameters of that population (e.g., selecting soil samples to characterize the properties at an environmental site). Sampling occurs at various levels and times throughout an environmental site characterization process. Typically, initial (primary) sampling occurs in the field while subsequent stages of sample size reduction (subsampling) occur until the final laboratory analysis stage. At each step in the measurement process, from planning, site selection, sample collection, sample preparation, through sample analysis, errors can occur that propagate, leading to uncertainty associated with the final result upon which decisions will ultimately be made. The goal of all sampling efforts should be to select samples that are representative of the population (i.e., site) in question. General guidelines, with supporting background and theory, for obtaining representative subsamples for the laboratory analysis of particulate materials using "correct" sampling practices and "correct" sampling devices are presented ("correct" as defined by Gy sampling theory; see Pitard 1993). Considerations are given to: the constitution and the degree of heterogeneity of the material being sampled, the methods used for sample collection (including what proper tools to use ), what it is that the sample is supposed to represent, the mass of the sample needed to be representative, and the bounds of what "representative" actually means.