Nonparametric correlation estimators as the Kendall and Spearman correlation are widely used in the applied sciences. They are often said to be robust, in the sense of being resistant to outlying observations. In this paper we formally study their robustness by means of their influence functions and gross-error sensitivities. Since robustness of an estimator often comes at the price of an incre...

OBJECTIVE To determine the correlation between pH and bicarbonate of soda in blood and saliva in child and adolescent patients during the administration of 3 g/m2 of methotrexate. METHOD A controlled clinical test was performed on 23 patients diagnosed with Acute Lymphoblastic Leukemia. Ages ranged from 4 to 18. The Spearman Correlation Coefficient was used to interpret the data. RESULTS No...

The objective of this paper is a study of performance of various techniques for correlation control when sampling from a multivariate population within the framework of Monte Carlo simulations, especially Latin Hypercube Sampling. In particular, we study the ability of the methods to fulfill the prescribed marginals and correlation structure of a random vector for various sample sizes. Two norm...

We examine a sample of 48 Swift/UVOT long Gamma-ray Burst light curves and find a correlation between the logarithmic luminosity at 200s and average decay rate determined from 200s onwards, with a Spearman rank coefficient of -0.58 at a significance of 99.998% (4.2σ). We discuss the causes of the log L200s − α>200s correlation, finding it to be an intrinsic property of long GRBs, and not result...

OBJECTIVE To translate into Arabic and validate the SF-36 quality of life index in a Tunisian Arabic population. BACKGROUND No validated Arabic quality of life index is published. DESIGN Arabic translation of the SF-36 scale was obtained by the "forward/backward translation" method. Adaptations were made after a pilot study involving 22 subjects from general population. Inter-rater reliabil...

BACKGROUND Current literature examining associations between vitamin D and chronic disease generally use a single assessment of 25-hydroxyvitamin D [25(OH)D], assuming the 25(OH)D concentration of an individual is consistent over time. METHODS We investigated the intraindividual variability between two measures of plasma 25(OH)D concentrations collected approximately five years apart (1997-20...

BACKGROUND AND PURPOSE Increased echogenicity of the substantia nigra is a typical transcranial sonography finding in Parkinson disease. Experimental software for digital analysis of the echogenic substantia nigra area has been developed. The aim of this study was to compare the evaluation of substantia nigra echogenicity by using digital analysis with a manual measurement in patients with Park...

BACKGROUND Many studies have explored the diagnostic performance of soluble suppression of tumorigenicity-2 (sST2) for heart failure (HF), but the results are inconsistent. Here, we performed a meta-analysis to assess the role of sST2 in the diagnosis of HF. METHODS We searched PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Database from incepti...

BACKGROUND Some publications suggest a strong correlation between the intracranial pressure and the intraocular pressure. Other studies claim no correlation between these two physiologic variables. Our aim was to study whether the tonometry could be a useful method to evaluate intracranial pressure in patients with suspected intracranial abnormality. METHODS We evaluated the correlation betwe...

The aim of this study was to analyse the correlation between external and internal mandibular morphology in adult or adolescent normal anthropological mandibles. Lateral radiographs of 31 symmetrical mandibles were analysed. The external morphology was defined by the gonial and beta-angles. In order to analyse internal morphology, a metallic pin was placed in the mental canal on the left side b...