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Biomedical subjects

F D McClure

Publications and source records attributed to F D McClure.

5 recordsLinked to original sources
PubMed1978

Usefulness of the stomacher in a microbiological regulatory laboratory.

The relative efficiency of the Waring blender, the Stomacher 400, and the Stomacher 3500 for preparing food samples for microbiological analysis was studied. Comparative aerobic plate count (APC) values were determined on 671 samples, representing 30 categories of foods. Of the 26 categories of nonfatty foods, the blender gave significantly higher geometric mean APC values than those given by the Stomacher 400 and the Stomacher 3500 in 65 and 69 percent of the categories, respectively. In a comparison of the two Stomacher models, the Stomacher 400 gave significantly higher geometric mean APC values than these given by the Stomacher 3500 in 73 percent of the food categories. Addition of Tween 80 to four categories of fatty foods at concentrations of 0.5, 1.0, and 2.0 percent did not raise the APC values given by either model of stomacher to the levels given by the Waring blender. Overall, the efficiency of both models of Stomacher, relative to the blender and to each other, was specific and depended upon the particular food being analyzed.

Bacteria↗
PubMedDate not supplied

Design and analysis of qualitative collaborative studies: minimum collaborative program.

Collaborative studies involving qualitative data are usually conducted under design constraints to fulfill the requirements for quantitative studies. The data from these qualitative studies are often analyzed in a manner that ignores the fact that collaborative studies involve matching (i.e., each laboratory analyzes a portion of each test sample). This report presents some design considerations and analysis procedures for qualitative collaborative studies that take into account that the design involves matching. Suggestions are offered as to the number of laboratories and test samples to use in the minimum collaborative program, and analysis procedures for outier screening are detailed. Method performance is assessed through such indicators as sensitivity, specificity, false positive, and false negative rates. Methods for estimating the error of the performance indicator rates are explained, and procedures are given for estimating false positive and false negative rates for lot defect rates that may occur in practice.

Chemistry Techniques, Analytical↗
PubMedDate not supplied

Statistical sampling approaches.

This article describes basic sampling principles and the application of statistical sampling techniques to specific problems encountered in the Food and Drug Administration (FDA). Concepts are emphasized, and theory is minimized. The basic principles of sampling from a normal and binomial population, including confidence interval calculation and sample size determination, are briefly reviewed. Stratified, random, systematic, and judgment sampling are explained. Operating characteristic curves for attribute (and perhaps variable) sampling for acceptance of lots are derived and applied to specific FDA problems. The advantages and disadvantages of single and multiple sampling plans and plans which address multiple classes of criteria such as major and minor defects are discussed. Sampling schedules such as MIL-STD-105D and Canada's Government Specifications Board CGSB-105-GP-1 are reviewed to familiarize readers with the principles involved in these plans and to give them an idea of how they could be applied to FDA problems.

Chemistry Techniques, Analytical↗