Simulación en el computador del teorema central de límite

El concepto de la Distribución de las Medias Muestrales, es sin lugar a dudas, el desarrollo de mayor trascendencia e importancia de la estadística clásica. Lo anterior es corroborado en todos los textos de estadística, en los cuales el desarrollo en cuestión, es descrito como el Teorema Central del Límite Sirwmhargn, y a pesar de que el teorema es fundamental en la teoría de la inferencia, el concepto resulta difícil de entender y ser asimilado, aún por estudiantes de pregrado en estadística, no obstante el énfasis que autores y profesores hacen con el propósito de procurar una buena asimilación y comprensión del terna, mediante la solución de ejercicios sobre comprensión del tema, mediante la solución de ejercicios sobre los cuales en la mayor parte de los casos se cae en una simple mecanización. En un esfuerzo por lograr una asimilación del teorema, en algunos textos se propone como ejercicio la toma sucesiva de muestras aleatorias del mismo tamaño y con reemplazamiento a partir de una población finita, en donde una vez estimadas las medias muestrales se procede a graficar su histograma con el fin de observar la forma de su distribución etc. Aunque el propósito del ejercicio es bueno, dicho ejercicio resulta sumamente tedioso debido a que en su ejecución se consume demasiado tiempo. Es justamente ésta la razón principal por la cual resulta de gran valor pedagógico el poder realizar dicha simulación con la ayuda del computador, pues en un tiempo relativamente muy corto, se pueden simular muchas muestras del mismo tamaño obteniendo, a partir de cada muestra las estimaciones básicas de los parámetros de la población entre ellos las de la media poblacional cuya distribución e histograma se pueden graficar. Rata simulación la han realizado estudiantes de los cursos de pregrado en Estadística I y II a mi cargo y el resultado observado ha sido satisfactorio desde el punto de vista de su propósito, ya que ha permitido al estudiante no solamente comprobar y asimilar rápidamente el concepto, sino que también ha ayudado a. generar ese sentimiento de credibilidad sobre la veracidad de los conceptos teóricos y a valorar la utilidad y la bondad dela estadística. En éste artículo, se presenta además de una breve reseña histórica, un enunciado clásico del teorema, una descripción de los resultados y en la parte final o apéndice, una presentación a manera de ejemplo de los resultados obtenidos con la simulación utilizando una de los archivos previamente grabados el cual contiene una población de 400 datos

A Guy Is A Guy

Purple pattern in background with photograph of Doris Dayhttps://scholarsjunction.msstate.edu/cht-sheet-music/6662/thumbnail.jp

Determinantes de la lealtad en la relación entre la Liga Antioqueña de Tenis de Campo y sus clientes

In order to have long-lasting relationships with their customers, sports organizations should make good marketing decisions based on studies that identify the characteristics of such relationships. In the literature, some studies have related the corporate environment to its sports counterpart, but few of them have investigated this kind of relationship using the set of constructs composed of satisfaction, perceived value, trust, commitment, and loyalty. Therefore, this paper analyzes the determinants of loyalty in the relationship between Liga Antioqueña de Tenis de Campo and its customers. This study adopted a mixed-methods approach divided into two stages: (1) exploration to understand the research problem and formulate the hypotheses and (2) description using a simple cross-sectional design with an analysis by Partial Least Squares Structural Equation Modeling (PLS-SEM). The results confirmed all the hypotheses proposed in the model, which included the determinants of loyalty suggested by relationship marketing in the sports context. This study found that, in the relationship between Liga Antioqueña de Tenis de Campo and its users, satisfaction, trust, and commitment are the direct determinants of loyalty and have a positive effect on it.Las organizaciones deportivas deben tomar decisiones acertadas en el ámbito del marketing, por lo que es necesario que dichas decisiones se basen en estudios que permitan identificar las características de las relaciones que mantienen con sus clientes, esto con el fin de que estas sean duraderas en el tiempo. En la literatura mundial se evidencian estudios que relacionan el entorno empresarial con el deportivo, pero pocos han estudiado este tipo de relación utilizando en su conjunto los constructos de satisfacción, valor percibido, confianza, compromiso y lealtad. Por lo tanto, este artículo pretende analizar los determinantes de la lealtad en la relación de la Liga Antioqueña de Tenis de Campo con sus clientes. La investigación se llevó a cabo a través de una metodología mixta que incluye dos fases: una fase exploratoria para comprender el problema de investigación y establecer las hipótesis, y otra descriptiva, de corte transversal simple, con análisis mediante un modelo de ecuaciones estructurales, bajo el enfoque de mínimos cuadrados parciales. El estudio arrojó una confirmación total de las hipótesis planteadas para el modelo, evidenciando los determinantes de la lealtad indicados por el marketing relacional en el contexto deportivo, específicamente en el de la Liga Antioqueña de Tenis de Campo y sus usuarios, encontrando que los determinantes directos de la lealtad, y que presentan un efecto positivo, son la satisfacción, la confianza y el compromiso

Reliability and validity of the Psychopathy Checklist-Revised in the assessment of risk for institutional violence: A cautionary note on DeMatteo et al. (2020).

A group of 12 authors (GA) shared a statement of concern (SoC) warning against the use of the Hare Psychopathy Checklist-Revised (PCL-R; Hare, 1991, 2003) to assess risk for serious institutional violence in US capital sentencing cases (DeMatteo et al., 2020). Notably, the SoC was not confined to capital sentencing issues, but included institutional violence in general. Central to the arguments presented in the SoC was that the PCL-R has poor predictive validity for institutional violence and also inadequate field reliability. The GA also identified important issues about the fallibility and inappropriate use of any clinical/forensic assessments, questionable evaluator qualifications, and their effects on capital sentencing decisions. However, as a group of forensic academics, researchers, and clinicians, we are concerned that the PCL-R represents a psycholegal red herring, while the SoC did not address critical legislative, systemic, and evaluator/rating issues that affect all risk assessment tools. We contend that the SoC’s literature review was selective and that the resultant opinions about potential uses and misuses of the PCL-R were ultimately misleading. We focus our response on the evidence and conclusions proffered by the GA concerning the use of the PCL-R in capital and other cases. We provide new empirical findings regarding the PCL-R’s predictive validity and field reliability to further demonstrate its relevance for institutional violence risk assessment and management. We further demonstrate why the argument that group data cannot be relevant for single-case assessments is erroneous. Recommendations to support the ethical and appropriate use of the PCL-R for risk assessment are provided

IFNL4 Genotypes and Risk of Childhood Burkitt Lymphoma in East Africa.

Interferon lambda 4 (IFN-λ4) is a novel type-III interferon that can be expressed only by carriers of the genetic variant rs368234815-dG within the first exon of the IFNL4 gene. Genetic inability to produce IFN-λ4 (in carriers of the rs368234815-TT/TT genotype) has been associated with improved clearance of hepatitis C virus (HCV) infection. The IFN-λ4-expressing rs368234815-dG allele (IFNL4-dG) is most common (up to 78%) in West sub-Saharan Africa (SSA), compared to 35% of Europeans and 5% of individuals from East Asia. The negative selection of IFNL4-dG outside Africa suggests that its retention in African populations could provide survival benefits, most likely in children. To explore this hypothesis, we conducted a comprehensive association analysis between IFNL4 genotypes and the risk of childhood Burkitt lymphoma (BL), a lethal infection-associated cancer most common in SSA. We used genetic, epidemiologic, and clinical data for 4,038 children from the Epidemiology of Burkitt Lymphoma in East African Children and Minors (EMBLEM) and the Malawi Infections and Childhood Cancer case-control studies. Generalized linear mixed models fit with the logit link controlling for age, sex, country, P. falciparum infection status, population stratification, and relatedness found no significant association between BL risk and 3 coding genetic variants within IFNL4 (rs368234815, rs117648444, and rs142981501) and their combinations. Because BL occurs in children 6-9 years of age who survived early childhood infections, our results suggest that additional studies should explore the associations of IFNL4-dG allele in younger children. This comprehensive study represents an important baseline in defining the health effects of IFN-λ4 in African populations

Antioxidant activity of twenty five plants from Colombian biodiversity

The antioxidant activity of the crude n-hexane, dichloromethane, and methanol extracts from 25 species belonging to the Asteraceae, Euphorbiaceae, Rubiaceae, and Solanaceae families collected at natural reserves from the Eje Cafetero Ecorregión Colombia, were evaluated by using the spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging method. The strongest antioxidant activities were showed by the methanol and dichloromethane extracts from the Euphorbiaceae, Alchornea coelophylla (IC50 41.14 mg/l) and Acalypha platyphilla (IC50 111.99 mg/l), respectively. These two species had stronger DPPH radical scavenging activities than hydroquinone (IC50 151.19 mg/l), the positive control. The potential use of Colombian flora for their antioxidant activities is discussed

Common genetic variants in the CLDN2 and PRSS1-PRSS2 loci alter risk for alcohol-related and sporadic pancreatitis

Pancreatitis is a complex, progressively destructive inflammatory disorder. Alcohol was long thought to be the primary causative agent, but genetic contributions have been of interest since the discovery that rare PRSS1, CFTR, and SPINK1 variants were associated with pancreatitis risk. We now report two significant genome-wide associations identified and replicated at PRSS1-PRSS2 (1×10-12) and x-linked CLDN2 (p < 1×10-21) through a two-stage genome-wide study (Stage 1, 676 cases and 4507 controls; Stage 2, 910 cases and 4170 controls). The PRSS1 variant affects susceptibility by altering expression of the primary trypsinogen gene. The CLDN2 risk allele is associated with atypical localization of claudin-2 in pancreatic acinar cells. The homozygous (or hemizygous male) CLDN2 genotype confers the greatest risk, and its alleles interact with alcohol consumption to amplify risk. These results could partially explain the high frequency of alcohol-related pancreatitis in men – male hemizygous frequency is 0.26, female homozygote is 0.07

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms