Plausible Indicators Research Articles

Saliva biomonitoring of atrazine exposure among herbicide applicators.

A field study was conducted in which saliva samples were collected from a cohort of herbicide applicators during the pre-emergent spray season in Ohio in 1996. Atrazine concentrations were detected in human saliva samples using an enzyme-linked immunosorbent assay (ELISA) method. Trend due to atrazine exposure and subsequent elimination in the body were evidenced by the temporal pattern of decreasing atrazine concentrations in saliva over time. Median salivary concentrations of atrazine on non-spray days were significantly lower than on spray days for each sampling time (Mann-Whitney U-Wilcoxon rank sum test, P < 0.01). Within spray days, median salivary atrazine concentrations were significantly higher on days atrazine was sprayed than on days herbicides other than atrazine were sprayed for each sampling time (Mann-Whitney U-Wilcoxon rank sum test, P = 0.02 for 4 6 p.m. samples, P = 0.04 for bedtime samples, P = 0.03 for next-morning samples). Median salivary atrazine concentrations on days atrazine was sprayed were higher than the median concentration for the corresponding sampling time on non-spray days and on days when other herbicides were sprayed. Salivary concentration of atrazine is a plausible indicator of those days in which atrazine spraying was likely to have occurred. Salivary concentrations of atrazine not only reflect exposures resulting from spraying atrazine, but also exposures from other field activities where applicators may come in contact with atrazine. The results of this study confirmed data from animal experiments that atrazine is able to cross the cell membranes of salivary glands, and can be measured in human saliva with high sensitivity. The sampling method itself is convenient and easy to use in the field, with a high compliance rate, and analytical procedures are rapid and inexpensive. It is, therefore, concluded that saliva sampling of atrazine exposure among herbicide applicators is a feasible biomonitoring method.

The Differences in Financial Structure Between Women- and Men-Owned Family Businesses

Lenders often are faced with the challenge of evaluating the financial success of a business or a proposed business by examining the financial records of the household, reasoning that an assessment of the household's financial position should be a plausible indicator of the financial status of the business. Utilizing data from the recently released Family Business Survey, this study uses financial information about both the family and the business to examine the relationship between household financial indicators and business financial indicators for women- and men-owned family businesses. The results suggest that, while household financial statements may be good indicators for men-owned businesses, they appear to be much less reliable for women-owned businesses.

Internal Validity Analysis: A Method for Adjusting Capture-Recapture Estimates of Prevalence

The authors propose a method for adjusting results of log-linear multi-source capture-recapture estimates of total population. The method compares the totals in some subpopulations of known size with estimates derived from various capture-recapture approaches to these subpopulations. The authors term such an approach an "internal validity analysis". Trends in the ratios of the estimates to the known true values of these subpopulations provide a plausible indicator of the bias of some types of estimates of the total population especially when underlying assumptions of the methods used have not been met in analysis of the total population. The authors apply this method to published data on an open population of injection drug users that had been previously analyzed with a standard capture-recapture analysis as if it were a closed population. Internal validity analysis suggests that the size of this population is about 15% greater than that previously estimated.

Bootstraps taxometrics. Solving the classification problem in psychopathology.

Classification in psychopathology is a problem in applied mathematics; it answers the empirical question "Is the latent structure of these phenotypic indicator correlations taxonic (categories) or nontaxonic (dimensions, factors)?" It is not a matter of convention or preference. Two taxometric procedures, MAMBAC and MAXCOV-HITMAX, provide independent tests of the taxonic conjecture and satisfactorily accurate estimates of the taxon base rate, the latent means, and the valid and false-positive rates achievable by various cuts. The method requires no gold standard criterion, applying crude fallible diagnostic "criteria" only in the phase of discovery to identify plausible candidate indicators. Confidence in the inference to taxonic structure and numerical accuracy of latent values is provided by multiple consistency tests, hence the term coherent cut kinetics for the general approach. Further revision of diagnostic systems should be based on taxometric analysis rather than on committee decisions based on clinical impressions and nontaxometric research.

Are Medication Error Rates Useful as Comparative Measures of Organizational Performance?

Although medication error rates seem a plausible indicator, it is not a foregone conclusion that error rates are good barometers of quality. This article is based on a multisite, nationwide study of one contributor to medication errors: pharmacy dispensing errors. Using questionnaires, directors of pharmacy at 157 member hospitals of a national health care management firm reported their average daily medication dispensing loads and the number of dispensing errors per 100 patient days during one quarter. Stepwise discriminant analysis was used to seek characteristics of high versus low reported error rates, as well as characteristics that could distinguish hospitals that reported no errors from those that reported errors. Results show that currently measured error rates represent a process within an organization and can range from no or few errors to substantial errors, with the variation reflecting a variety of scenarios. Hospitals that do not measure error rates obviously report no errors. Inattention or a lack of clear methods to collect and define errors can also result in no reported errors or low error rates. In contrast, a hospital that standardizes and implements a measurement scheme may have high reported error rates. Progressive experimentation with systemwide error prevention and process improvement will result in varying error rates. Logically, if hospitals are punished for reporting high error rates, they will start reporting lower error rates regardless of the true rates. Finally, successful management practices will be reflected in low error rates. The focus on measuring medication error rates is important for improving quality within organizations because drug-related errors are an important cause of adverse events. However, the variances in error-reporting rates and the variables associated with those variances documented in this study raise serious questions about the usefulness of comparing error rates between hospitals based on voluntary reports. Interorganizational comparisons of rates are not likely to be meaningful and may be counterproductive.

Magnetic effects in non-relativistic quantum electrodynamics: image corrections to the electron moment

Conventional non-relativistic quantum electrodynamics is used to calculate position-dependent corrections to the magnetic moment of an electron a distance z from a perfectly conducting surface. To leading order, delta mu /sub ///=-e3/32m2z and delta mu z=0. These results follow easily and without any special pleading from the usual Foldy-Wouthuysen Hamiltonian, and are validated by necessarily much more elaborate relativistic calculations using either the full quantum field theory, or Dirac single-particle theory. Together with a recent non-relativistic account of the free-electron anomalous moment, such agreement is interpreted as a plausible indication that non-relativistic quantum electrodynamics is at least qualitatively adequate to deal with magnetic radiative effects, on the same footing as it can deal with non-magnetic analogues like the Lamb shift.