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Background: Parametric regression analysis is widely used in methods comparisons and more recently in checking the concordance of test results following receipt of new reagent lots. The greater frequency of reagent-lot evaluations increases pressure to detect bias with smallest possible sample sizes (i.e. smallest consumption of time and resources). This study revisits bias detection using the joint slope, intercept confidence region as an alternative to slope and intercept confidence intervals. Methods: Four cases were considered representing constant errors, proportional errors (constant CV) and two more complicated error patterns typical of immunoassays. Maximum:minimum range ratios varied from 2:1 to 2000:1. After setting a maximum tolerable difference a series of slope, intercept combinations, each of which predicted the critical difference, were systematically evaluated in simulations which determined the minimum sample size required to detect the difference, firstly using slope, intercept confidence intervals and secondly using the joint slope, intercept confidence region. Results: At small to moderate range ratios, bias detection by joint confidence region required greatly reduced sample sizes to the extent that it should encourage reagent-lot evaluations or, alternatively, transform those already routinely performed into considerably less costly exercises. Conclusions: While some software is available to calculate joint confidence regions in real-life analyses, shifting this testing method into the mainstream will require a greater number of software developers incorporating the necessary code into their regression programs. The computer program used to conduct this study is freely available and can be used to model any laboratory test. [ABSTRACT FROM AUTHOR]

The contemporary portrayals of cityscapes on television create a 'postcard effect', a way of seeing that affords the viewer the pleasure of a tourist gaze. This disposition both reflects and legitimizes a fragmented experience of visiting a location without immersing oneself in the intricacies of its politics and geography.

Serum concentrations of several nutrients were measured in 12 captive wild felid species including caracal (Felis caracal), cheetah (Acinonyx jubatus), cougar (Fells concolor), fishing cat (Fells viverrinus), leopard (Panthera pardus), lion (Panthera leo), ocelot (Fells pardalis), pallas cat (Fells manul), sand cat (Fells margarita), serval (Felis serval), snow leopard (Panthera uncia) and tiger (Panthera tigris). Diet information was collected for these animals from each participating zoo (Brookfield Zoo, Fort Worth Zoo, Lincoln Park Zoological Gardens and North Carolina Zoological Park). The nutritional composition of the diets at each institution met the probable dietary requirements for each species except for the pallas cat. Blood samples were collected from each animal (n = 69) and analyzed for lipids (total cholesterol, triacylglycerides, HDL cholesterol and LDL cholesterol), vitamin D metabolites [25-hydroxycholecalciferol (25(OH)D) and 1,25-dihydroxycholecalciferol (1,25(OH)2D)], vitamin A (retinol, retinyl stearate and retinyl palmitate), vitamin E ([alpha]- and [gamma]-tocopherol) and selected carotenoids. Species differences were found for all except triacylglycerides and 1,25(OH)2D. Genus differences were found for retinol, retinyl palmitate, retinyl stearate, [gamma]-tocopherol and [beta]-carotene. Circulating nutrient concentrations for many of the species in this study have not been reported previously and most have not been compared with the animals' dietary intakes. The large number of animals analyzed provides a substantial base for comparing the serum nutrient concentrations of healthy animals, for both wild and captive exotic species. KEY WORDS: * Fells * lipids * vitamin A * vitamin D * vitamin E

Proposes six principles to follow when teaching students to think. Aimed at teaching thinking as an indivisible process rather than as a set of discrete skills, the principles involve active learning, the articulation of thinking, intuitive understanding, structuring courses developmentally, motivating learning, and establishing a positive learning environment. (PGD)

The cognitive skills approach to teaching college students, which seeks to train intelligence by explicitly developing learning and thinking skills, has been effectively used in the recent past and students taught by this method have spoken appreciatively of it. Intense verbal interaction is a distinctive feature of the approach. (MSE)

Background: Bland-Altman analysis is a popular and widely used method for assessing the level of agreement between two analytical methods. An important assumption is that paired method differences exhibit approximately constant (homogeneous) scatter when plotted against pair means. This allows estimation of limits of agreement which retain validity across the entire range of mean values. In practice, pair differences often increase systematically with the mean and Bland and Altman used log transformed data to achieve approximately homogeneous scatter. Unfortunately, a logarithmic transformation fails when data are located near the detection limit of an assay (a region that is often of considerable clinical importance).Methods: Simulated thyrotropin data are used to illustrate how a variance function, estimated from pair differences, can be used to transform problematic data into a form suitable for traditional Bland-Altman analysis. Simulated and real data sets are used in a supplementary file to illustrate and offer practical solutions to potential problems.Results: Following transformation by variance function, Bland-Altman results can be readily interpreted by back-transformation either to the original measurement scale or as percentage values. Limits of agreement are no longer horizontal straight lines, but their shapes simply reflect error characteristics which are (or should be) thoroughly familiar to laboratory analysts.Conclusions: The method is completely general and in principle requires only the estimation of a variance function that reliably describes the relationship between the variances of pair differences and their mean values. A computer program is available which performs the necessary calculations. [ABSTRACT FROM AUTHOR]

This article examines the positive effects of sports education upon alienated youth. The author explores the concept of alienation within youth culture and then links it to relevant sports' programs. The author also examines sports as a movement of play, and uses this perception as a baseline for the development of sports programs in response to alienation. He suggests that sports need not be entirely focused on the mitigation of alienation among youth, and notes the importance of personal growth and reflection communicated during the instruction of sports.

Background: Implementing International Organization for Standardization definitions of limit of blank and limit of detection requires precision estimates from specimens devoid of analyte (blank specimens) and also from specimens located close to zero. Calculations are straightforward if errors are constant over the relevant concentration range but estimation of the relationship between variability and concentration (variance function) is necessary in the general case when errors are not constant. This study investigated the efficacy of incorporating the variance function into estimation of limit of blank, limit of detection and their confidence intervals.Methods: Simulated data, designed to encompass the range of properties that would typically be observed in practice, consisted of four distinct relationships between variance and concentration, in combination with large and small variances and three concentration ranges. Four methods of estimating limit of blank were evaluated together with the accuracy of variance function derived estimates of limit of detection and the accuracy of symmetrical 95% confidence intervals constructed from limit of blank and limit of detection constituent variables.Results: Most limit of blank estimates and all limit of detection estimates showed systematic negative bias but, provided the data concentration range is not too small, the biases were consistently <1% with confidence interval coverages ranging from 92% to 95%. Estimating limit of blank by extrapolating the variance function to zero lost little in comparison with methods based on blank specimen data.Conclusions: The variance function provides a convenient and reliable way of analyzing data from experiments evaluating detection capability and, provided certain assumptions are tenable, of estimating limit of blank and limit of detection as part of routine internal quality control. [ABSTRACT FROM AUTHOR]