The Likelihood Ratio Test and Full Bayesian Significance Test under small sample sizes for contingency tables

Hypothesis testing in contingency tables is usually based on asymptotic results, thereby restricting its proper use to large samples. To study these tests in small samples, we consider the likelihood ratio test and define an accurate index, the P-value, for the celebrated hypotheses of homogeneity, independence, and Hardy-Weinberg equilibrium. The aim is to understand the use of the asymptotic results of the frequentist Likelihood Ratio Test and the Bayesian FBST -- Full Bayesian Significance Test -- under small-sample scenarios. The proposed exact P-value is used as a benchmark to understand the other indices. We perform analysis in different scenarios, considering different sample sizes and different table dimensions. The exact Fisher test for $2 \times 2$ tables that drastically reduces the sample space is also discussed. The main message of this paper is that all indices have very similar behavior, so the tests based on asymptotic results are very good to be used in any circumstance, even with small sample sizes

Characterising dirichlet priors

The characterisation of prior distributions is a problem that has been discussed since Bayes published his paper. Bayes himself tried to justify his prior following a principle that became known as principle of insucient reason. In the last century, several applied researchers used conjugated priors mainly for mathematical convenience while others still tried to justify their choices based on reasonable principles of inference and/or key features, depending on the problem at hand. This work justifies the use of Dirichlet priors based on a principle called partition invariance, alongside with other requirements that are already well known from the literature

Designs of Early Phase Cancer Trials with Drug Combinations

We discuss several innovative phase I and phase I--II designs for early phase cancer clinical trial with drug combinations focusing on continuous dose levels of both agents. For phase I trials with drug combinations, the main objective is to estimate the maximum tolerated dose (MTD) curve in the two-dimensional Cartesian plane. A parametric model is used to describe the relationship between the doses of the two agents and the probability of dose-limiting toxicity (DLT). Trial design proceeds using cohorts of two patients receiving doses according to univariate escalation with overdose control (EWOC) or continual reassessment method (CRM). At the end of the trial, the MTD is estimated as a function of Bayes estimates of the model parameters. Furthermore, we present the model where a fraction of DLTs can be attributed to one or both agents, and show how the parametric designs can be adapted to account for an unknown fraction of attributable DLTs. We also consider the inclusion of a binary baseline covariate to describe sub-groups with different frailty levels. In phase I--II trials, it may not be possible to evaluate efficacy in a short window of time. In this case, two-stage designs are frequently employed. First, a set of maximum tolerated dose combinations is selected. Next, the selected set is then tested for efficacy, sometimes in a different patient population than that used in the first stage. We discuss binary and time-to-event endpoints to identify dose combinations along the MTD curve with maximum probability of efficacy in the second stage

Cointegration and unit root tests: A fully Bayesian approach

To perform statistical inference for time series, one should be able to assess if they present deterministic or stochastic trends. For univariate analysis one way to detect stochastic trends is to test if the series has unit roots, and for multivariate studies it is often relevant to search for stationary linear relationships between the series, or if they cointegrate. The main goal of this article is to briefly review the shortcomings of unit root and cointegration tests proposed by the Bayesian approach of statistical inference and to show how they can be overcome by the fully Bayesian significance test (FBST), a procedure designed to test sharp or precise hypothesis. We will compare its performance with the most used frequentist alternatives, namely, the Augmented Dickey-Fuller for unit roots and the maximum eigenvalue test for cointegration. Keywords: Time series; Bayesian inference; Hypothesis testing; Unit root; Cointegration

Processo de Gestão Estratégica em Universidades Privadas: Um estudo de casos STRATEGIC MANAGEMENT PROCESS IN PRIVATES UNIVERSITIES: A CASES STUDY

O objetivo deste artigo é descrever e compreender como a Gestão Estratégica (GE) é desenhada, implementada e monitorada em universidades privadas. A análise dos dados revelou quais os fatores que afetam o processo de GE nessas universidades, suas características, os atores envolvidos no processo e, finalmente, a relação entre planejamento e desempenho. Os resultados indicam que em duas universidades estudadas (casos A e B) a GE é um processo consolidado e foi concebido para se desenvolver uma visão de futuro e auxiliar as organizações a lidarem com os desafios ambientais. Em contraste, no terceiro caso (C), os resultados indicam que a GE não se encontra ainda no mesmo nível de maturidade dos casos relatados anteriormente. Normal 0 21 false false false PT-BR X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabela normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The aim of this article is to describe and understand how Strategic Management is designed, implemented and monitored in private universities. The data analysis has revealed which factors have affected the Strategic Management process in these universities, its characteristics, the actors involved in this process and, finally, the relationship between planning and performance. The results have also shown that in two universities (cases A and B) their Strategic Management is already a mature process, which was designed in order to create a vision of the future and help both universities to deal with environmental pressures. By contrast, the third case (C) revealed that its Strategic Management has not reached yet the same level of maturity observed in the other two cases.</p

Processo de Gestão Estratégica em Universidades Privadas: Um estudo de casos

The aim of this article is to describe and understand how Strategic Management is designed, implemented and monitored in private universities. The data analysis has revealed which factors have affected the Strategic Management process in these universities, its characteristics, the actors involved in this process and, finally, the relationship between planning and performance. The results have also shown that in two universities (cases A and B) their Strategic Management is already a mature process, which was designed in order to create a vision of the future and help both universities to deal with environmental pressures. By contrast, the third case (C) revealed that its Strategic Management has not reached yet the same level of maturity observed in the other two cases.O objetivo deste artigo é descrever e compreender como a Gestão Estratégica (GE) é desenhada, implementada e monitorada em universidades privadas. A análise dos dados revelou quais os fatores que afetam o processo de GE nessas universidades, suas características, os atores envolvidos no processo e, finalmente, a relação entre planejamento e desempenho. Os resultados indicam que em duas universidades estudadas (casos A e B) a GE é um processo consolidado e foi concebido para se desenvolver uma visão de futuro e auxiliar as organizações a lidarem com os desafios ambientais. Em contraste, no terceiro caso (C), os resultados indicam que a GE não se encontra ainda no mesmo nível de maturidade dos casos relatados anteriormente

Orthodontic Treatment in Children with Cerebral Palsy

Cerebral palsy is a permanent neuromuscular motor disorder that gives rise to many functional problems, including impaired swallowing, chewing and speech. Maxillary transverse deficiency and Angle Class II malocclusion are common. Some of these functional problems can be due to maxillary malocclusion. To our knowledge, no case series has yet been published on orthodontic treatment in children with cerebral palsy. In this chapter, we provide an overview of this topic based on the literature and on our own clinical experience. We consider that some patients with cerebral palsy are susceptible to orthodontic treatment. The keys to success are appropriate patient selection, based on anatomical, physiological and behavioural characteristics, and the degree of involvement of parents and caregivers. Among parents of cerebral palsy children undergoing orthodontic therapy, the perceived level of overall satisfaction was very high and expectations were often exceeded; however, these results are conditioned by factors such as the Peer Assessment Rating (PAR) index. Although some authors reported improvements in aesthetics, speech and oral function, an objective assessment of functional improvement is still lacking. In our experience, correction of resting position and management of neuromuscular alterations are essential if successful orthodontic treatment is to be achieved and relapses avoided

Differential Features of Culprit Intracranial Atherosclerotic Lesions: A Whole-Brain Vessel Wall Imaging Study in Patients With Acute Ischemic Stroke.

BackgroundIntracranial atherosclerotic disease tends to affect multiple arterial segments. Using whole-brain vessel wall imaging, we sought to study the differences in plaque features among various types of plaques in patients with a recent unilateral anterior circulation ischemic stroke.Methods and resultsSixty-one patients with unilateral anterior circulation ischemic stroke were referred to undergo whole-brain vessel wall imaging (before and after contrast) within 1&nbsp;month of symptom onset for intracranial atherosclerotic disease evaluations. Each plaque was classified as a culprit, probably culprit, or nonculprit lesion, according to its likelihood of causing the stroke. The associations between plaque features (thickening pattern, plaque-wall contrast ratio, high signal on T1-weighted images, plaque contrast enhancement ratio, enhancement grade, and enhancement pattern) and culprit lesions were estimated using mixed multivariable logistic regression after adjustment for maximum wall thickness. In 52 patients without motion corruption in whole-brain vessel wall imaging, a total of 178 intracranial plaques in the anterior circulation were identified, including 52 culprit lesions (29.2%), 51 probably culprit lesions (28.7%), and 75 nonculprit lesions (42.1%). High signal on T1-weighted images (adjusted odds ratio, 9.1; 95% confidence interval, 1.9-44.1; P=0.006), grade 2 (enhancement ratio of plaque ≥ enhancement ratio of pituitary) contrast enhancement (adjusted odds ratio, 17.4; 95% confidence interval, 1.8-164.9; P=0.013), and type 2 (≥50% cross-sectional wall involvement) enhancement pattern (adjusted odds ratio, 10.1; 95% confidence interval, 1.3-82.2; P=0.030) were independently associated with culprit lesions.ConclusionsHigh signal on T1-weighted images, grade 2 contrast enhancement, and type 2 enhancement pattern are associated with cerebrovascular ischemic events, which may provide valuable insights into risk stratification

Antibiotic Prophylactic Regimens for Infective Endocarditis in Patients Undergoing Dental Procedures

Up to date causal relationship has been demonstrated between dental manipulations and the onset of infective endocarditis (IE). However, since 1955, numerous expert committees have proposed antibiotic prophylaxis (AP) to prevent bacteraemia of oral origin. Controversy regarding the efficacy of AP prior to the dental procedures has intensified in recent years because of the lack of conclusive evidence on its efficacy for the prevention of IE and on its cost-effectiveness, as well as the possibility of allergic reactions and the emergence of antibiotic resistance. Accordingly, AP is now maintained exclusively for patients at highest risk and who require the manipulation of the gingival or periapical regions of the teeth or perforation of the oral mucosa. In the context of a restrictive policy, the National Institute for Health and Clinical Excellence (NICE) of the United Kingdom published a new guideline in 2008 stating that “AP against IE is not recommended for persons undergoing dental procedures”, regardless of risk status and of the nature of the procedure to be performed. The NICE guideline has generated further controversy, and expert committees in other countries continue to publish prophylactic regimens for the prevention of IE secondary to dental procedures. In this chapter, we discuss the principal guidelines currently applicable in Europe, the USA and Australia, and we draw particular attention to the need for randomised clinical trials