Insulin resistance is a treatable precursor of diabetes and potentially of cardiovascular disease as well. To identify insulin-resistant patients, we developed decision rules from measurements of obesity, fasting glucose, insulin, lipids, and blood pressure and family history in 2,321 (2,138 nondiabetic) individuals studied with the euglycemic insulin clamp technique at 17 European sites; San Antonio, Texas; and the Pima Indian reservation. The distribution of whole-body glucose disposal appeared to be bimodal, with an optimal insulin resistance cutoff of <28 mol/min ⅐ kg lean body mass. Using recursive partitioning, we developed three types of classification tree models: the first, based on clinical measurements and all available laboratory determinations, had an area under the receiver operator characteristic curve (aROC) of 90.0% and generated a simple decision rule: diagnose insulin resistance if any of the following conditions are met: BMI >28.9 kg/m 2 , homeostasis model assessment of insulin resistance (HOMA-IR) >4.65, or BMI >27.5 kg/m 2 and HOMA-IR >3.60. The fasting serum insulin concentrations corresponding to these HOMA-IR cut points were 20.7 and 16.3 U/ml, respectively. This rule had a sensitivity and specificity of 84.9 and 78.7%, respectively. The second model, which included clinical measurements but no laboratory determinations, had an aROC of 85.0% and generated a decision rule that had a sensitivity and specificity of 78.7 and 79.6%, respectively. The third model, which included clinical measurements and lipid measurements but not insulin (and thus excluded HOMA-IR as well), had a similar aROC (85.1%), sensitivity (81.3%), and specificity (76.3%). Thus, insulin-resistant individuals can be identified using simple decision rules that can be tailored to specific needs. Diabetes 54:333-339, 2005 T here is abundant evidence that insulin resistance is a precursor of type 2 diabetes (1,2) and perhaps of cardiovascular disease as well (3-5). The latter association, which is independent of diabetes, may be partially a consequence of the relationship between insulin resistance and the "metabolic syndrome," which consists of obesity, particularly abdominal obesity; impaired glucose regulation; dyslipidemia of the high-triglyceride/low-HDL cholesterol type; and hypertension (4,6).A number of techniques are available for making definitive measurements of insulin resistance, including the hyperinsulinemic-euglycemic clamp technique (7), the frequently sampled intravenous glucose tolerance test (8), and the insulin suppression test (9,10). These techniques, however, are complicated, cumbersome, and, in general, not suitable for large-scale population studies or routine clinical work. For that reason a wide variety of indexes based on simpler, clinical measurements have been proposed for assessing insulin resistance. We recently reviewed a number of these indexes (11). Most have been validated with either the euglycemic clamp or the frequently sampled intravenous glucose tolerance test, but the populations ...

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Escherichia coli were isolated from the faeces of 266 individuals living in the Canberra region of Australia. The isolates were characterized for their ECOR group membership (A, B1, B2 or D) and for the presence of 29 virulence-associated traits. Overall, 19?5 % of the strains were members of group A, 12?4 % B1, 45?1 % B2 and 22?9 % D. The frequency with which strains belonging to the four ECOR groups were observed varied with the age and sex of the hosts from which they were isolated. In males, the probability of isolating A or D strains increased with host age, whilst the probability of detecting a group B2 strain declined. In females, the probability of recovering A or B2 strains increased with increasing host age and there was a concomitant decline in the likelihood of isolating B1 or D strains. Of the 29 virulence-associated traits examined, 24 were detected in more than one strain. The likelihood of detecting most traits varied with a strain's ECOR membership, with the exception of afa/draBC, astA, cvaC, eaeA, iss and iutA, for which there was no statistically significant evidence of an association with ECOR group. The frequency with which fimH, iha, eaeA, iroN, hlyD, iss, ompT and K1 were detected in a strain depended on the age or sex of the host from which the strain was isolated. In group B2 strains many of the virulence traits were non-randomly associated, with some co-occurring in a strain less often than expected by chance, whilst others were co-associated. In 17 cases, the extent to which two virulence traits were co-associated was found to depend on host sex and age. The results of this study suggest that the morphological, physiological and dietary differences that occur among human individuals of different sex or age may influence the distribution of E. coli genotypes.

The authors propose two methods based on the signed root of the likelihood ratio statistic for one-sided testing of a simple null hypothesis about a scalar parameter in the presence of nuisance parameters. Both methods are third-order accurate and utilise simulation to avoid the need for onerous analytical calculations characteristic of competing saddlepoint procedures. Moreover, the new methods do not require specification of ancillary statistics. The methods respect the conditioning associated with similar tests up to an error of third order, and conditioning on ancillary statistics to an error of second order. RÉSUMÉ Les auteurs proposent deux méthodes permettant,à partir de la racine signée du rapport des vraisemblances, d'effectuer un test unilatéral d'une hypothèse nulle simple sur un paramètre d'échelle, en présence de paramètres nuisibles. Par le biais de simulations, ces méthodes permettent d'obtenir une précision du troisième ordre tout enévitant les calculs analytiques lourds caractéristiques des méthodes de point de selle concurrentes; elles n'exigent pas non plus la spécification de statistiques libres. Les méthodes proposées respectent, au troisième ordre, le conditionnement associé aux tests similaires, ainsi que celui sur les statistiques libres, mais au deuxième ordre seulement.

Financial illiteracy is widespread amongst the elderly. Financially illiterate people are more likely to experience asset loss and outlive their savings after retirement. This paper measures financial literacy of elderly Australians using Item Responses Theory. Using a Lasso regression, we find that younger, married males with higher income and greater net wealth are more likely to be financially literate. Better financial literacy is also associated with good health, higher educational attainment, better occupation and outright home ownership. Our findings suggest policy makers take action and we make informed and practicable policy recommendations.

Motivated by problems of frontier estimation in productivity analysis, and boundary estimation in scatter-point image analysis, we consider polynomial-based estimators of the edge of a distribution. Our aim is to develop methods for correcting polynomial-type estimators of bias, and for constructing simultaneous confidence bands for the data edge. We tackle this problem by first deriving large-sample approximations to distributions of polynomial-based edge estimators, and then developing algorithms for simulating from them so as to produce Monte Carlo approximations to the distribution of the difference between the true edge and its estimator. This involves applying representations for joint extreme value distributions. The majority of attention is focused on the parametric case, but nonparametric problems, where polynomial approximations are fitted locally, are also considered.1998 Academic Press

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For inference about a multidimensional parameter 1/; in the presence of nuisance parameters, the usual log-profile-likelihood function M( 1/;) is often replaced by an objective Op(l). It is shown in this paper that under mild conditions on the adjustment function B (1/;) both frequentist and Bayesian Bartlett correction are possible for the adjusted likelihood ratio statistic arising from M( 1/;). General formulae for the Bartlett adjustment factors are developed, and these formulae are evaluated for some specific adjustment functions B(1/;). Furthermore, conditions under which the frequentist and Bayesian adjustment factors agree to order are considered. In particular, prior probability density functions for which the highest posterior density region of posterior probability content 1 -ex has frequentist coverage level l-ex+O(n-2 ) are characterized, and similar characterizations are given for likelihood-based regions.