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Aim: To assess the social cognitive elements of the stigma of mental illness (knowledge, attitudes and behaviours) among healthcare professionals (HCPs) in Jordan. Design: A cross‐sectional descriptive design. Methods: A total of 206 HCPs were conveniently recruited from general hospitals in Jordan. The mental attitude, knowledge and intended behaviours scales were used to measure stigma elements. Results: Participants reported a moderate level of knowledge, a moderate negative attitude and a moderate or not greater interest to deal with people with mental health illnesses. The bivariate correlation revealed a negative significant correlation between HCPs' knowledge and attitude, indicating that HCPs with more knowledge significantly have more positive attitude (lower average score) towards those suffering from the illness. A more significant correlation was found between HCPs' knowledge and behaviour. The HCPs who had more knowledge were holding more interest and willingness towards dealing with persons with mental illness. Patient or Public Contribution: Negative attitudes among HCPs demand awareness programmes pertaining to the stigma of mental illness to afford higher standards of practice for patients with mental problems. [ABSTRACT FROM AUTHOR]

Consumption of unhealthy commercial foods and beverages (UCFB) is common among infants and young children living in low- and middle-income countries. Such foods can displace other nutritious foods, however, there is limited evidence on how this consumption tracks across time. This study assessed and tracked UCFB consumption of children living in rural/peri-urban Cambodia during the complementary feeding period, identified UCFB consumption patterns of these children, and explored the association between UCFB consumption and growth. A 6-month longitudinal cohort study was implemented among 567 caregivers of children aged 10-14 months at recruitment. UCFB consumption was estimated each month via a telephone-administered 7-day food frequency questionnaire, and UCFB consumption patterns were identified based on changes in this frequency of consumption over time. The majority of children either maintained (45.7%, n = 246) or developed (43.5%, n = 234) an unhealthy consumption pattern and only 10.8% (n = 58) of children maintained/transitioned into a healthy consumption pattern. High consumers of UCFB at 10-14 months had a 4.7 (CI: 4.7 [3.1-7.2]) times odds of being high consumers of UCFB at 15-19 months (p < 0.001). There was a trend of lower length- for-age z-scores (LAZ) among children maintaining or developing an unhealthy consumption pattern (~-0. SD LAZ) compared to children maintaining/transitioning into a healthy consumption pattern, however, this association was not statistically significant. Findings indicate that high UCFB consumption begins during infancy and tracks into early childhood. National policies and programmes centred on early interventions addressing the use of UCFB for infant and young child feeding are needed. [ABSTRACT FROM AUTHOR]

The article discusses several manifestations of risk within audit sampling procedures, suggesting they are more conceptually significant than commonly theoretically proposed. The implications of risk analysis on sampling methods and the advantages of dollar-unit sampling in particular are described in depth. Several factors of sampling selection are considered, including population characteristic assumptions, the levels of specificity in procedure design, and test objectives. The possibilities of tangible risk within the sampling population, of non-applicability to variable assignment, and error distribution patterns are addressed, providing numerical examples.

Vitamin B6 is important in fetal development, but little is known of the vitamin B6 status of pregnant women and newborns in North America and potential modifying factors. This prospective study determined maternal and cord plasma concentrations of pyridoxal 5′ phosphate (PLP; an indicator of vitamin B6 status) in a convenience sample of 368 Canadian pregnant women and their newborns. The association of maternal intake of vitamin B6 and fetal genetic variants with cord plasma PLP and homocysteine concentrations was also examined. Dietary and supplemental intakes of vitamin B6 were assessed in early and mid to late pregnancy. PLP concentrations were measured in maternal plasma in early pregnancy and at delivery, and in cord plasma. Six fetal variants of the MTHFR and CβS genes were assessed for their association with cord plasma PLP and homocysteine concentrations. Geometric mean (95% CI) PLP concentrations were 107 (98, 116) nmol/L in early pregnancy and 58 (53, 62) nmol/L at delivery, respectively, and 296 (275, 319) nmol/L in cord blood ( p < .0001). During early pregnancy and at delivery, 3.6% and 5.5% of women had plasma PLP concentrations <20 nmol/L, respectively. Ninety eight percent of the women with supplemental B6 intake of at least the recommended dietary allowance had PLP concentrations >20 nmol/L. Fetal genetic variants were not associated with cord PLP and homocysteine concentrations. Vitamin B6 deficiency is uncommon in a cohort of Canadian pregnant women due largely to prevalent vitamin B6 supplement use. [ABSTRACT FROM AUTHOR]

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Context and objective Shared decision making is especially advocated for preference-sensitive decisions. We investigated whether physicians' recommendations pull patients away from their preferred treatment option when making a preference-sensitive decision. Design, participants and methods Inpatients ( N = 102 with schizophrenia, N = 101 with multiple sclerosis) were presented with a hypothetical scenario (the choice between two drugs). They were first asked about their preferences concerning the two drugs and then they received a (fictitious) clinician's recommendation that was contrary to their preferences. Subsequently they made a final choice between the two drugs. Main outcome measures The main outcome measure was whether the patient followed the physician's advice in the hypothetical scenario. Thereby patient's (pre-recommendation) preferences served as a baseline. Results In the decision scenario, about 48% of the patients with schizophrenia and 26% of the patients with multiple sclerosis followed the advice of their physician and thus chose the treatment option that went against their initial preferences. Patients who followed their physician's advice were less satisfied with their decision than patients not following their physician's advice (schizophrenia: t = 2.61, P = 0.01; multiple sclerosis: t = 2.67, P = 0.009). Discussion and conclusions When sharing decisions with patients, physicians should be aware that their advice might influence patients' decisions away from their preferred treatment option. They should encourage their patients to identify their own preferences and help to find the treatment option most consistent with them. [ABSTRACT FROM AUTHOR]

This study was designed to assess brain-derived neurotrophic factor (BDNF) as a possible candidate for enhanced cognition in breastfed infants. The study was conducted on 42 infants, 4-6 months old, who were classified according to their feeding pattern into breastfed group, formula-fed group and mixed-feeding group. Each infant was subjected to history taking, clinical examination, estimation of the level of BDNF by Enzyme-Linked Immunosorbent Assay (ELISA) technique and assessment by Bayley scale of infant development-second edition (BSID-II). The current study revealed that breastfed group had higher BSID-II scores followed by mixed-fed group then formula-fed one, yet these results reached statistical significance only in total behaviour rating scale (TBRS) and Motor Quality Percentile rank values. Additionally, breastfed infants had significantly higher values of BDNF when compared to those receiving formula milk. Negative correlations between BDNF and both weight for age and weight for length scores were detected. Furthermore, significant positive correlation was detected between BDNF and TBRS. Regression analysis studies revealed that breastfeeding is the most determinant factor for BDNF, TBRS and Motor Quality Percentile rank values. Serum BDNF levels are significantly higher in breastfed infants and shows positive correlations with the results of BSID-II. Given that simultaneous increase in brain BDNF occurs due to onsite production, transport from the periphery or both, it is prudent to hypothesize that BDNF could be one of the factors responsible for the enhanced cognition detected in breastfed infants. [ABSTRACT FROM AUTHOR]

Objectives: This study examined selected effects of the proper use of nonparametric inferential statistical methods for analysis of nonnormally distributed data, as exemplified by emergency department length of stay (ED LOS). The hypothesis was that parametric methods have been used inappropriately for evaluation of ED LOS in most recent studies in leading emergency medicine (EM) journals. To illustrate why such a methodologic flaw should be avoided, a demonstration, using data from the National Hospital Ambulatory Medical Care Survey (NHAMCS), is presented. The demonstration shows how inappropriate analysis of ED LOS increases the probability of type II errors. Methods: Five major EM journals were reviewed, January 1, 2004, through December 31, 2007, and all studies with ED LOS as one of the reported outcomes were reviewed. The authors determined whether ED LOS was analyzed correctly by ascertaining whether nonparametric tests were used when indicated. An illustrative analysis of ED LOS was constructed using 2006 NHAMCS data, to demonstrate how inferential testing for statistical significance can deliver differing conclusions, depending on whether nonparametric methods are used when indicated. Results: Forty-nine articles were identified that studied ED LOS; 80% did not perform a test of normality on the ED LOS data. Data were not normally distributed in all 10 of the studies that did perform such tests. Overall, 43% failed to use appropriate nonparametric methods. Analysis of NHAMCS data confirmed that failure to use nonparametric bivariate tests results in type II statistical error and in multivariate models with less explanatory power (a smaller R 2 value). Conclusions: ED LOS, a key ED operational metric, is frequently analyzed incorrectly in the EM literature. Applying parametric statistical tests to such nonnormally distributed data reduces power and increases the probability of a type II error, which is the failure to find true associations. Appropriate use of nonparametric statistics should be a core component of statistical literacy because such use increases the validity of ED research and quality improvement projects. ACADEMIC EMERGENCY MEDICINE 2010; 17:1113-1121 © 2010 by the Society for Academic Emergency Medicine [ABSTRACT FROM AUTHOR]

The study of differences among groups is an interesting statistical topic in many applied fields. It is very common in this context to have data that are subject to mechanisms of loss of information, such as censoring and truncation. In the setting of a two-sample problem with data subject to left truncation and right censoring, we develop an empirical likelihood method to do inference for the relative distribution. We obtain a nonparametric generalization of Wilks' theorem and construct nonparametric pointwise confidence intervals for the relative distribution. Finally, we analyse the coverage probability and length of these confidence intervals through a simulation study and illustrate their use with a real data set on gastric cancer. [ABSTRACT FROM AUTHOR]

ACADEMIC EMERGENCY MEDICINE 2010; 17:940–950 © 2010 by the Society for Academic Emergency Medicine Objectives: The objectives of this study were to determine concordance of emergency department (ED) management of acute myocardial infarction (AMI) with guideline recommendations and to identify ED and patient characteristics predictive of higher guideline concordance. Methods: The authors conducted a chart review study of ED AMI care as part of the National Emergency Department Safety Study (NEDSS). Using a primary hospital discharge diagnosis of AMI (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM], codes 410.XX), a random sample of ED visits for AMI in 58 urban EDs across 20 U.S. states between 2003 and 2006 were identified. Concordance with American College of Cardiology/American Heart Association (ACC/AHA) guideline recommendations was evaluated using five individual quality measures and a composite concordance score. Concordance scores were calculated as the percentage of eligible patients who received guidelines-recommended care. These percentage scores were rescaled from 0 to 100, with 100 indicating perfect concordance. Results: The cohort consisted of 3,819 subjects; their median age was 65 years, and 62% were men. The mean (± standard deviation [SD]) ED composite concordance score was 61 ± 8), with a broad range of values (42 to 84). Except for aspirin use (mean concordance, 82), ED concordance scores were low (beta-blocker use, 56; timely electrocardiogram [ECG], 41; timely fibrinolytic therapy, 26; timely ED disposition for primary percutaneous coronary intervention [PCI] candidates, 43). In multivariable analyses, older age (beta-coefficient per 10-year increase, −1.5; 95% confidence interval [CI] = −2.4 to −0.5) and southern EDs (beta-coefficient, −5.2; 95% CI = −9.6 to −0.9) were associated with lower guideline concordance, whereas ST-segment elevation on initial ED ECG was associated with higher guideline concordance (beta-coefficient, 3.6; 95% CI = 1.5 to 5.7). Conclusions: Overall ED concordance with guideline-recommended processes of care was low to moderate. Emergency physicians should continue to work with other stakeholders in AMI care, such as emergency medical services (EMS) and cardiologists, to develop strategies to improve care processes. [ABSTRACT FROM AUTHOR]

This paper considers inference in a broad class of nonregular models. The models considered are nonregular in the sense that standard test statistics have asymptotic distributions that are discontinuous in some parameters. It is shown in Andrews and Guggenberger (2009a) that standard fixed critical value, subsampling, and m out of n bootstrap methods often have incorrect asymptotic size in such models. This paper introduces general methods of constructing tests and confidence intervals that have correct asymptotic size. In particular, we consider a hybrid subsampling/fixed-criticalvalue method and size-correction methods. The paper discusses two examples in detail. They are (i) confidence intervals in an autoregressive model with a root that may be close to unity and conditional heteroskedasticity of unknown form and (ii) tests and confidence intervals based on a post-conservative model selection estimator. [ABSTRACT FROM AUTHOR]

Conventional bootstrap- t intervals for density functions based on kernel density estimators exhibit poor coverages due to failure of the bootstrap to estimate the bias correctly. The problem can be resolved by either estimating the bias explicitly or undersmoothing the kernel density estimate to undermine its bias asymptotically. The resulting bias-corrected intervals have an optimal coverage error of order arbitrarily close to second order for a sufficiently smooth density function. We investigated the effects on coverage error of both bias-corrected intervals when the nominal coverage level is calibrated by the iterated bootstrap. In either case, an asymptotic reduction of coverage error is possible provided that the bias terms are handled using an extra round of smoothed bootstrapping. Under appropriate smoothness conditions, the optimal coverage error of the iterated bootstrap- t intervals has order arbitrarily close to third order. Examples of both simulated and real data are reported to illustrate the iterated bootstrap procedures. [ABSTRACT FROM AUTHOR]

Comparison of two samples can sometimes be conducted on the basis of analysis of receiver operating characteristic (ROC) curves. A variety of methods of point estimation and confidence intervals for ROC curves have been proposed and well studied. We develop smoothed empirical likelihood-based confidence intervals for ROC curves when the samples are censored and generated from semiparametric models. The resulting empirical log-likelihood function is shown to be asymptotically chi-squared. Simulation studies illustrate that the proposed empirical likelihood confidence interval is advantageous over the normal approximation-based confidence interval. A real data set is analysed using the proposed method. [ABSTRACT FROM AUTHOR]

The two-stage design is popular in epidemiology studies and clinical trials due to its cost effectiveness. Typically, the first stage sample contains cheaper and possibly biased information, while the second stage validation sample consists of a subset of subjects with accurate and complete information. In this paper, we study estimation of a survival function with right-censored survival data from a two-stage design. A non-parametric estimator is derived by combining data from both stages. We also study its large sample properties and derive pointwise and simultaneous confidence intervals for the survival function. The proposed estimator effectively reduces the variance and finite-sample bias of the Kaplan–Meier estimator solely based on the second stage validation sample. Finally, we apply our method to a real data set from a medical device postmarketing surveillance study. [ABSTRACT FROM AUTHOR]

Forecasting population decline to a certain critical threshold (the quasi-extinction risk) is one of the central objectives of population viability analysis (PVA), and such predictions figure prominently in the decisions of major conservation organizations. In this paper, we argue that accurate forecasting of a population's quasi-extinction risk does not necessarily require knowledge of the underlying biological mechanisms. Because of the stochastic and multiplicative nature of population growth, the ensemble behaviour of population trajectories converges to common statistical forms across a wide variety of stochastic population processes. This paper provides a theoretical basis for this argument. We show that the quasi-extinction surfaces of a variety of complex stochastic population processes (including age-structured, density-dependent and spatially structured populations) can be modelled by a simple stochastic approximation: the stochastic exponential growth process overlaid with Gaussian errors. Using simulated and real data, we show that this model can be estimated with 20–30 years of data and can provide relatively unbiased quasi-extinction risk with confidence intervals considerably smaller than (0,1). This was found to be true even for simulated data derived from some of the noisiest population processes (density-dependent feedback, species interactions and strong age-structure cycling). A key advantage of statistical models is that their parameters and the uncertainty of those parameters can be estimated from time series data using standard statistical methods. In contrast for most species of conservation concern, biologically realistic models must often be specified rather than estimated because of the limited data available for all the various parameters. Biologically realistic models will always have a prominent place in PVA for evaluating specific management options which affect a single segment of a population, a single demographic rate, or different geographic areas. However, for forecasting quasi-extinction risk, statistical models that are based on the convergent statistical properties of population processes offer many advantages over biologically realistic models. [ABSTRACT FROM AUTHOR]

This article gives conditions under which the nonparametric instrumental variables estimator of Hall and Horowitz ( Annals of Statistics 33 (December 2005), 2904–2929) is asymptotically normally distributed. With sufficiently large samples, the asymptotic normality result can be used to form confidence intervals for the unknown function that is estimated by the Hall–Horowitz procedure. The article reports the results of a Monte Carlo investigation of the finite-sample coverage probabilities of the confidence intervals. [ABSTRACT FROM AUTHOR]

The large deviation modified likelihood ratio statistic is studied for testing a variance component equal to a specified value. Formulas are presented in the general balanced case, whereas in the unbalanced case only the one-way random effects model is studied. Simulation studies are presented, showing that the normal approximation to the large deviation modified likelihood ratio statistic gives confidence intervals for variance components with coverage probabilities very close to the nominal confidence coefficient. [ABSTRACT FROM AUTHOR]

Procédure de tests multiples utilisant les probabilités des contre-hypothèses unilatérales, avec application aux études génomiques Cet article vise à faire le lien entre l'analyse bayésienne et la théorie fréquentiste dans le contexte des comparaisons multiples. Les auteurs montrent que lorsque l'on teste l'égalité de deux moyennes, la probabilité a posteriori de la contre-hypothèse unilatérale, définie comme un demi-espace, partage avec le seuil observé la propriété d'uniformité sous l'hypothèse nulle. Ultimement, la probabilité a posteriori peut donc être utilisée dans le même esprit qu'un seuil observé dans le cadre de la procédure de Benjamini-Hochberg et dans chacune de ses généralisations. [ABSTRACT FROM AUTHOR]

A U-statistic is not easy to apply or cannot be applied in hypothesis testing when it is degenerate or has an indeterminate degeneracy under the null hypothesis. A class of two-stage U-statistics (TU-statistics) is proposed to remedy these drawbacks. Both the asymptotic distributions under the null and the alternative of TU-statistics are shown to have simple forms. When the degeneracy is indeterminate, the Pitman asymptotic relative efficiency of a TU-statistic dominates that of the incomplete U-statistics. If the kernel is degenerate under the null hypothesis but non-degenerate under the alternative, a TU-statistic is proved to be more powerful than its corresponding U-statistic. Applications to testing independence of paired angles in ecology and marine biology are given. Finally, a simulation study shows that a TU-statistic is more powerful than its corresponding incomplete U-statistic in almost all cases under two settings. [ABSTRACT FROM AUTHOR]

The likelihood ratio statistic for testing pointwise hypotheses about the survival time distribution in the current status model can be inverted to yield confidence intervals (CIs). One advantage of this procedure is that CIs can be formed without estimating the unknown parameters that figure in the asymptotic distribution of the maximum likelihood estimator (MLE) of the distribution function. We discuss the likelihood ratio-based CIs for the distribution function and the quantile function and compare these intervals to several different intervals based on the MLE. The quantiles of the limiting distribution of the MLE are estimated using various methods including parametric fitting, kernel smoothing and subsampling techniques. Comparisons are carried out both for simulated data and on a data set involving time to immunization against rubella. The comparisons indicate that the likelihood ratio-based intervals are preferable from several perspectives. [ABSTRACT FROM AUTHOR]

We simulated the effects of missing information on statistical distributions of animal response that covaried with measured predictors of habitat to evaluate the utility and performance of quantile regression for providing more useful intervals of uncertainty in habitat relationships. These procedures were evaluated for conditions in which heterogeneity and hidden bias were induced by confounding with missing variables associated with other important processes, a problem common in statistical modeling of ecological phenomena. Simulations for a large (N = 10000) finite population representing grid lo- cations on a landscape demonstrated various forms of hidden bias that might occur when the effect of a measured habitat variable on some animal was confounded with the effect of another unmeasured variable. Quantile (0 ≤ τ ≤ 1) regression parameters for linear models that excluded the important, unmeasured variable revealed bias relative to parameters from the generating model. Depending on whether interactions of the measured and unmeasured variables were negative (interference interactions) or positive (facilitation interactions) in simulations without spatial structuring, either upper (τ > 0.5) or lower (τ < 0.5) quantile regression parameters were less biased than mean rate parameters. Heterogeneous, nonlinear response patterns occurred with correlations between the measured and unmeasured variables. When the unmeasured variable was spatially structured, variation in parameters across quantiles associated with heterogeneous effects of the habitat variable was reduced by modeling the spatial trend surface as a cubic polynomial of location co- ordinates, but substantial hidden bias remained. Sampling (n 20-300) simulations demonstrated that regression quantile estimates and confidence intervals constructed by inverting weighted rank score tests provided valid coverage of these parameters. Local forms of quantile weighting were required for obtaining correct Type I error rates and confidence interval coverage. Quantile regression was used to estimate effects of physical habitat resources on a bivalve (Macomona liliana) in the spatially structured landscape on a sandflat in a New Zealand harbor. Confidence intervals around predicted 0.10 and 0.90 quantiles were used to estimate sampling intervals containing 80% of the variation in densities in relation to bed elevation. Spatially structured variation in bivalve counts estimated by a cubic polynomial trend surface remained after accounting for the nonlinear effects of bed elevation, indicating the existence of important spatially structured processes that were not adequately represented by the measured habitat variables. [ABSTRACT FROM AUTHOR]

The article presents a study that deals with a distribution theory for likelihood-ratio statistics for the comparison of several treatments with a control. The study assumes that the sample sizes on the treatments are equal while the sample size on the control as large. It presents the results of a study comparing a one-sided t-test, the likelihood-ratio test, and Dunnett's one-sided test.

The purpose of this note is to give a simple method for forming confidence intervals for certain Poisson ratios. Some possible applications are found in marketing research, quality control and biology. the proportion of type 1 to type 2 customers arriving to be serviced would be another obvious case. The interesting relations among some of the well known probability distributions was exhibited. A procedure for constructing a confidence interval for the true proportion was given.