Selection and application of statistical methods in medical research / 上海预防医学

Statistics plays an important role in medical research， and the selection of appropriate statistical methods is crucial for drawing reliable and valuable conclusions. This paper provides a brief introduction to commonly used statistical analysis methods for medical data， covering descriptive analysis， parametric test， nonparametric test， correlation analysis， regression analysis， and analysis of survival data. It focuses on discussing the assumptions of multiple linear regression， logistic regression and Cox proportional risk regression， as well as how to choose the appropriate statistical methods for analyzing and interpreting medical data based on different research objectives and data types.

Una medida de variación para datos cualitativos con cualquier tipo de distribución

Existe muchas medidas de variación para datos nominales, pero son poco conocidas cuando este tipo de datos son comunes en ciencias sociales y de la salud. Entre estas medidas, destacan el índice de variación cualitativa (IVC) de Gibbs y Poston, la razón de variación (RV) de Freeman, la razón de variación de la moda (RVMod) de Wilcox, la entropía relativa (ERel) de Shannon y la desviación estándar desde la moda (DEM) de Kvalseth. El objetivo del artículo es proponer una modificación de la razón de variación que supere la limitación a distribuciones unimodales de las fórmulas de Freeman y Wilcox; asimismo, describir el patrón de comportamiento de los seis índices. Al nuevo índice se denomina razón de variación universal (RVU), ya que es válido para cualquier tipo de distribución con datos cualitativos. Se observa que RV, RVU, RVMod y DEM se aproximan rápidamente a 0 cuando hay una moda muy definida con proximidad a la distribución de una variable aleatoria constante. Por el contrario, ERel y ICV se aproximan rápidamente a 1 cuando hay múltiples modas o proximidad a una distribución uniforme con una moda única. Se concluye que, entre las seis medidas, DEM y RVU son las mejores.

There are many measures of variation for nominal data, but they are little known, when this type of data is common in health and social science research. Among these measures, the Gibbs-Poston's qualitative variation index (QVI), the Freeman's variation ratio (VR), the Wilcox's variation ratio from the mode (VRMod), the Shannon's relative entropy (ERel), and the Kvalseth's standard deviation from the mode (SDM) stand out. The objective of this article is to propose a modification of the variation ratio that overcomes the limitation to unimodal distributions of Freeman and Wilcox formulas; also describe the behavior pattern of the six indices. This new index is named the universal variation ratio (UVR), since it is valid for any type of distribution with qualitative data. It is observed that RV, UVR, RVMod and DEM quickly approach 0 when there is a very defined mode with proximity to the distribution of a constant random variable. On the contrary, ERel and QVI quickly approach 1 when there are multiple modes or proximity to a uniform distribution with a unique mode. It is concluded that, among six indices, SDM and UVR are the best measures.

Existem muitas medidas de variação para dados nominais, mas são pouco conhecidas, quando este tipo de dados é comum em pesquisas em saúde e ciências sociais. Entre essas medidas, o índice de variação qualitativa de Gibbs-Poston (IVQ), a razão de variação de Freeman (VR), a razão de variação da moda de Wilcox (RVMod), a entropia relativa de Shannon (ERel) e o desvio padrão da moda de Kvalseth (DPM) se destacam. O objetivo deste artigo é propor uma modificação da razão de variação que supere a limitação a distribuições unimodais das fórmulas de Freeman e Wilcox; também descreve o padrão de comportamento dos seis índices. Esse novo índice é denominado razão de variação universal (RVU), pois é válido para qualquer tipo de distribuição com dados qualitativos. Observa-se que RV, RVU, RVMod e DPM rapidamente se aproximam de 0 quando existe um modo muito definido com proximidade da distribuição de uma variável aleatória constante. Pelo contrário, ERel e IVQ rapidamente se aproximam de 1 quando há vários modos ou proximidade de uma distribuição uniforme com uma moda única. Conclui-se que, entre seis índices, DPM e RVU são as melhores medidas.

Revisión bibliométrica de COVID-19 en el periodo diciembre 2019 y julio 2020 / A bibliometric review of COVID-19 from december 2019 to july 2020

Resumen Objetivo: realizar el análisis bibliométrico de COVID-19 durante diciembre de 2019 a 30 de junio de 2020. Métodos: revisión bibliométrica del total de la literatura y de lo relacionado con COVID-19 en las bases Pubmed, Scopus y Lilacs durante el periodo diciembre de 2019 a 30 junio de 2020. Se clasificaron los artículos por categorías (objetivo, país, especialidad) y se compararon con la literatura del año anterior. Resultados: se encontraron 27 373, 16 944 y 1083 publicaciones acerca de COVID-19 en Pubmed, Scopus y Lilacs respectivamente. La principal especialidad médica por búsqueda fue neumología. De acuerdo con el objetivo, el más encontrado fue tratamiento (50.0%). El país con más publicaciones fue Estados Unidos (28.9%) en Pubmed y Scopus. En el lapso COVID-19 las publicaciones de la enfermedad representan 0.06 del total. Conclusiones: existe un volumen importante de publicaciones relacionadas con COVID-19 en periodo de estudio, equivalente a 6% de las publicaciones totales, lo cual es significativo para una sola enfermedad.(Acta Med Colomb 2020; 45. DOI:https://doi.org/10.36104/amc.2020.1879).

Abstract Objective: to perform a bibliometric analysis of COVID-19 from December 2019 to June 30, 2020. Methods: a bibliometric review of all the literature and COVID-19 related material in the PubMed, Scopus and Lilacs databases from December 2019 to June 30, 2020. Articles were classified by categories (objective, country, specialty) and compared to the previous year's literature. Results: a total of 27,373, 16,944 and 1,083 publications on COVID-19 were found in PubMed, Scopus and Lilacs, respectively. The main medical specialty by search was pulmonology. The most frequently found objective was treatment (50.0%). The country with most publications was the United States (28.9%) on PubMed and Scopus. During the COVID-19 span, publications on the disease represented 0.06 of the total. Conclusions: there was a significant volume of COVID-19 related publications during the study period, equivalent to 6% of the total publications, which is significant for a single disease.(Acta Med Colomb 2020; 45. DOI:https://doi.org/10.36104/amc.2020.1879).

O uso da análise de correspondências múltiplas (ACM) na pesquisa: o auxílio da tabela de proporções condicionais / The use of multiple correspondence analysis (MCA) in research: the aid of conditional proportions table

A análise de correspondências múltiplas (ACM) é uma técnica pertinente para a psicologia, pois permite estudar associações entre diversas variáveis categóricas tais como características individuais e respostas a questionários, produzindo um mapa que permite visualizá-las. No entanto, é frequentemente mal interpretada, pois trabalha com um nível alto de dimensões, o que torna difícil verificar os dados originais. O trabalho apresenta uma técnica auxiliar para a ACM, a tabela de proporções condicionais, que apresenta as proporções das variáveis incluídas isoladamente e em relações bivariadas, possibilitando a identificação de associações e sua magnitude de modo concreto. O trabalho inclui a aplicação empírica de análise de atribuições de tarefas domésticas a homens e mulheres, proveniente de pesquisa com 958 adultos que forneceram opiniões em levantamento de dados realizado no interior do Brasil. A principal contribuição da tabela de proporções condicionais está no esforço de tornar mais acessível e precisa a utilização da ACM para pesquisadores de psicologia.

Multiple correspondence analysis (MCA) is a relevant technique for psychology, since it allows the study of associations among various categorical variables such as individual characteristics or questionnaires responses, producing a map that makes it possible to visualize them. However, it is often misinterpreted as it deals with a high level of dimensions that makes it difficult to verify the original data. The paper presents an auxiliary technique for MCA, the conditional proportions table, which presents the proportions of the included variables in isolation and in bivariate relationships, enabling the identification of associations and their size in a concrete way. The paper includes an empirical application of the analysis of the attribution of domestic tasks to men and women, from a study with 958 adults who provided their opinions on a survey carried out in the Brazilian countryside. The main contribution of the conditional proportions table lies in the effort of making the use of MCA more accessible and precise for psychology researchers.

Descriptive statistics and normality tests for statistical data

Descriptive statistics are an important part of biomedical research which is used to describe the basic features of the data in the study. They provide simple summaries about the sample and the measures. Measures of the central tendency and dispersion are used to describe the quantitative data. For the continuous data, test of the normality is an important step for deciding the measures of central tendency and statistical methods for data analysis. When our data follow normal distribution, parametric tests otherwise nonparametric methods are used to compare the groups. There are different methods used to test the normality of data, including numerical and visual methods, and each method has its own advantages and disadvantages. In the present study, we have discussed the summary measures and methods used to test the normality of the data.

Spatial variation of chemical attributes in archaeological dark earth under cocoa cultivation in Western Amazon / Variação espacial de atributos químicos em terra pr eta arqueológica sob cultivo de cacau na amazonia ocide ntal

As Terras Pretas Arqueológicas (TPAs) são solos de fertilidade que notoriamente são superiores à grande maioria dos solos típicos da região amazônica. Assim, o uso das TPAs intensificou-se devido às características químicas apresentadas por esses solos, como a alta concentração de nutrientes (fósforo, cálcio, magnésio). Nesse sentido, o objetivo deste estudo foi avaliar a distribuição espacial dos atributos químicos do solo em uma área de Terra Preta Arqueológica sob cultivo de cacau no município de Apuí (AM). O mapeamento de uma malha de 42 x 88 m, com espaçamento irregular de 6 x 8 m, totalizando 88 pontos, foi realizado e, em seguida, foram coletadas amostras de solo nas profundidades de 0,0-0,05; 0,05-0,10; (pH, O.C, Sto. C, (H + Al), P, K, Ca, Mg, SB, CEC e V%). Os dados foram analisados por meio de técnicas estatísticas descritivas e geoestatísticas. Os valores médios e medianos foram ajustados aos valores próximos, indicando distribuição normal, enquanto os atributos químicos do solo foram ajustados aos modelos de semivariogramas esféricos e exponenciais. A maioria dos atributos apresentou coeficiente de variação (CV) entre 12,1 e 60%, caracterizada como variabilidade média, as variáveis do estudo apresentaram diferentes faixas e a maioria teve forte dependência espacial. As técnicas geoestatísticas utilizadas permitiram os ajustes dos modelos teóricos que melhor representaram a semivariância experimental, possibilitando a construção de mapas temáticos da distribuição espacial dos valores dos atributos da área estudada.

The Black Archaeological Lands (TPAs) are fertility soils that are notoriously superior to the vast majority of typical soils in the Amazon region. Thus, the use of TPAs ​​has intensified due to the chemical characteristics presented by these soils, such as the high concentration of nutrients (phosphorus, calcium, magnesium). In this sense, the objective of this study was to evaluate the spatial distribution of the chemical attributes of the soil in an area of ​​Terra Preta Arqueológica under cocoa cultivation in the city of Apuí (AM). The mapping of a mesh of 42 x 88 m, with irregular spacing of 6 x 8 m, totaling 88 points, was carried out and, then, soil samples were collected at depths of 0.0-0.05; 0.05-0.10; (pH, O.C, Sto. C, (H + Al), P, K, Ca, Mg, SB, CEC and V%). The data were analyzed using descriptive and geostatistical statistical techniques. The mean and median values ​​were adjusted to the close values, indicating normal distribution, while the chemical attributes of the soil were adjusted to the models of spherical and exponential semivariograms. Most of the attributes presented a variation coefficient (CV) between 12.1 and 60%, characterized as average variability, the study variables had different ranges and most had a strong spatial dependence. The geostatistical techniques used allowed the adjustments of the theoretical models that best represented the experimental semivariance, allowing the construction of thematic maps of the spatial distribution of the values ​​of the attributes of the studied area.

Significación social de un entorno virtual para la enseñanza - aprendizaje de la Estadística descriptiva en la carrera de Medicina / Social significance of a virtual environment for the teaching and learning of descriptive Statistics in Medicine degree course

Los estudios de ciencia, tecnología y sociedad revelan las interrelaciones entre la ciencia y la tecnología como procesos sociales. Este artículo persigue como objetivo: valorar la significación social de un entorno virtual en la enseñanza aprendizaje de la Estadística descriptiva en la carrera de Medicina. El diagnóstico preliminar mediante de la observación, la encuesta y el análisis documental, mostró que existen insuficiencias en el uso de las tecnologías de la información y las comunicaciones en el proceso de enseñanza aprendizaje de la Estadística. Se diseñó un entorno virtual constituido por cinco módulos que incluyen contenidos de Estadística descriptiva, ejercicios, bibliografía y ayuda. Con la validación a partir del criterio de especialistas y la sistematización con la introducción en la práctica, se evaluó el mismo como muy adecuado, fue considerado útil, necesario y aplicable al contexto objeto de estudio, lo que contribuye a la formación científica de los estudiantes desde una posición materialista.

Science, technology and society studies reveal the interrelations between science and technology as social processes. This article pursues the following objectives: to assess the social significance of a virtual environment in the teaching and learning of descriptive Statistics in Medicine degree course. The preliminary diagnosis through the observation, opinion poll and documentary analysis, showed that there are insufficiencies in the use of Information and Communication technologies in teaching and learning Statistics. It was designed a virtual environment with five modules that include contents of descriptive Statistics, exercises, bibliography and help. With the validation of specialists and the systematization after putting it in practice, the virtual environment was assessed as adequate, useful, necessary and applicable to the context being studied, which contributes to the scientific training of students from a materialistic position.

Estatística descritiva: perguntas que você sempre quis fazer, mas nunca teve coragem / Descriptive statistics: questions you have always wanted to ask, but never had the courage to

A revista do HCPA (Clinical & Biomedical Research) está reabrindo a seção de Bioestatística com o intuito de apresentar artigos explicativos, conceituais ou tutoriais, de modo a elucidar os leitores sobre os mais diversos temas estatísticos. Neste contexto, este artigo será o primeiro de uma série que tem como objetivo responder algumas das questões mais levantadas por pesquisadores da área da saúde. Começando pela Estatística Descritiva, alguns conceitos são esclarecidos e diversas referências são indicadas para o estudo do tema e para análises em SPSS ou R-project. (AU)

The HCPA journal (Clinical & Biomedical Research) is reopening its Biostatistics section with the aim of presenting readers with explanatory, conceptual or tutorial articles on a wide range of statistical topics. In this context, this is the first in a series of articles seeking to answer some of the questions raised by health researchers. Starting with descriptive statistics, some concepts are introduced and several references are indicated for those interested in studying the topic and performing analyses in SPSS or R-project. (AU)

Description of continuous data using bar graphs: a misleading approach

With the ease provided by current computational programs, medical and scientific journals use bar graphs to describe continuous data.

Role of Statistics in Multidisciplinary Research – With Reference to Psychological Research.

Statistics is the study of the collection, organization, analysis, interpretation and presentation of data. It deals with all aspects of data. It is usually noticed that some routine words are given technical meanings in statistical parlance (e.g. “mean,” “normal,” “significance,” “effect,” and “power”). It is essential to resist the temptation of conflating their technical meanings. A failure to do so may have a lot to do with the ready acceptance of the “effect size” and “power” arguments in recent years. As, statistics is used (i) to describe data in terms of the shape, central tendency, and dispersion of their simple frequency distribution, and (ii) to make decisions about the properties of the statistical populations on the basis of sample statistics. Statistical decisions are made with reference to a body of theoretical distributions: the distributions of various test statistics that are in turn derived from the appropriate sample statistics. In every case, the calculated test statistic is compared to the theoretical distribution, which is made up of an infinite number of tokens of the test statistic in question. Hence, the “in the long run” caution should be made explicit in every probabilistic statement based on inferential statistics (e.g. “the result is significant at the 0.05 level in the long run”).Despite the recent movement to discourage psychologists from conducting significance tests, significance tests can be defended by (i) clarifying some concepts, (ii) examining the role of statistics in empirical research, and (iii) showing that the sampling distribution of the test statistic is both the bridge between descriptive and inferential statistics and the probability foundation of significance tests. The present paper discusses the critical issues of statistics in psychological research.

Using GIS to Assess the Contribution of Farming Activities towards Climate Change in the State of Mississippi.

The study uses primary data, descriptive statistics, Geographic Information Systems (GIS) and correlation analysis to analyze the contributions of farming activities to climate change in Mississippi between 1992 through 2002. This involved the assessment of methane emissions from rice cultivation in the state of Mississippi as well as the relationship between the levels of methane gas concentration and other variables associated with rice production. In highlighting the extent to which rice production activities fuel climate change, the results of the study not only showed greenhouse gas emission related rice production activities to be on the rise, but there is a relationship between methane emissions and rice farming. The GIS analysis also points to a visible concentration of rice production activities associated with methane emissions in the major counties of Bolivia, Sunflower and Washington along the Northwest portion of the state. While this raises the threats of climate change predictors in the area. To remedy the problems, the paper suggests five future lines of actions from the need for education to the promotion of emission trading.

Intervalos de ittegración unificados para la caacterización estructural de pettróleos, carbones o sus fracciones por rmn ¹h y rmn 13c / Unified inegratiion intervls for the structural characterization of oil, coal or fractions there of by 1h nmr and 13c nmr / Intervalos de integração unificados para a caracterização estrutural de petróleos, carvões ou suas frações por rmn ¹h e rmn 13c

Con base en la revisión de publicaciones, hechas entre 1972 y 2006, se evidenció que hay imprecisiones en los límites de los intervalos de integración que los autores asignan a las señales en resonancia magnética nuclear (RMN) para hacer la caracterización estructural de petróleos, carbones o sus fracciones derivadas, a partir de sus espectros de hidrógeno (RMN ¹H) o de carbono (RMN 13C). En consecuencia, se determinaron límites unificados para la integración de los espectros RMN ¹H y RMN 13C de tales muestras mediante un tratamiento estadístico aplicado a los límites de los intervalos de integración ya publicados. Con esos límites unificados se elaboraron cartas de correlación en RMN útiles para la asignación de la integral en esos intervalos, y aun en otros de menor extensión definidos en función de la intersección entre asignaciones diferentes. Además se plantearon ecuaciones necesarias para establecer la integral atribuible a fragmentos más específicos en un intento por hacer una caracterización estructural más exacta a partir de los espectros RMN de petróleos, carbones o sus fracciones deriva.

Based on an analysis of publications reported between 1972 and 2006, it became clear that there are inaccuracies in the limits of the ranges of integration that the authors assigned to signals in nuclear magnetic resonance (NMR) to the structural characterization of petroleum, coals and their derived fractions, from their hydrogen (¹H NMR) and carbon (13C NMR) spectra. Consequently, consolidated limits were determined for the integration of ¹H NMR spectra and 13C NMR of these samples using a statistical treatment applied to the limits of integration intervals already published. With these unified limits, correlation NMR charts were developed that are useful for the allocation of the integral at such intervals, and at smaller intervals defined in terms of the intersection between different assignments. Also raised equations needed to establish the integral attributable to specific fragments in an attempt to make a more accurate structural characterization from NMR spectra of oil, coal or fractions derived.

Com base na revisão de publicações, feitas entre 1972 e 2006, evidenciou-se que existem imprecisões nos limites dos intervalos de integração que os autores tem atribuído aos sinais de ressonância magnética nuclear (RMN) para a caracterização estrutural do petróleo, carvão ou suas frações derivadas, com base em seus espectros de hidrogênio (RMN ¹H) e carbono (RMN 13C). Conseqüentemente, determinaram-se os limites consolidados para a integração dos espectros de RMN ¹H e RMN 13C deste tipo de amostras usando um tratamento estatístico aplicado aos limites de intervalos de integração já publicados. Com estes limites unificados foram desenvolvidos gráficos de correlação em RMN úteis para a atribuição da integral nestes intervalos e em outros menores, definidos em termos de intersecção entre atribuições diferentes. Além do mais, levantaram-se equações necessárias para estabelecer a integral atribuível a fragmentos específicos, numa tentativa de fazer uma caracterização estrutural mais exata a partir de espectros RMN de petróleo, carvão ou frações derivadas.

Caracterização das queimadas acidentais em campo, no Município de Santa Maria-RS / Characterization of accidental field burns in the county of Santa Maria - RS, Brazil

Neste trabalho o objetivo foi realizar um estudo de queimadas acidentais em campo, foi para identificar, caracterizar e localizar lugares de maior ocorrência dessas na cidade de Santa Maria-RS, com intuito de auxiliar no planejamento e controle de incêndios. A variável de interesse foi o número de chamadas recebidas, por dia, pelo Corpo de Bombeiros de Santa Maria, no período de 1° de janeiro de 1993 a 31 de dezembro de 2004. Verificou-se que, em média, o Corpo de Bombeiros recebeu 1,81 chamadas diárias; que antes da ocorrência de uma chamada não chovia, em média, há quatro dias; a grande maioria ocorreu no período da tarde e às margens das rodovias que circundam a cidade, principalmente, na RS 287, rodovia com margens pouco habitadas. O mês em que ocorreu o maior número de chamadas ao Corpo de Bombeiros foi agosto, sendo o ano de 1999, o que acumulou maior ocorrência de queimadas. Além disso, o número de chamadas distribui-se uniformemente nos dias da semana. As margens das rodovias e os bairros Distrito Industrial, Medianeira, Itararé, Tomazzetti e Parque Pinheiro Machado foram as áreas com maiores chances de ocorrência de queimadas.

The objetive of this research was to conduct a study on accidental field burns in the county of Santa Maria-RS, Brazil to identify and characterize sites where they most frequently occur with the objective of helping in the planning and controlling of those burns. The variable of interest was the number of daily calls received by the Santa Maria Fire Department, from January 1st 1993 to December 31st 2004. It was observed that the Fire Department received on average 1.81 daily calls; that the calls were followed by a dry period of four days, on average; and most calls occurred during the afternoon and alongside the almost unhabited RS 287 highway. The month with the highest number of calls was August, and the year 1999 presented the highest occurrence number of field burns. Finally, the number of calls was equally distributed along the weekdays. The margins of the highways and the following city districts: Distrito Industrial, Medianeira, Itararé, Tomazzetti and Parque Pinheiro Machado presented the highest chances of burnings occurrence.

THE DIAGNOSTIC VALUE OF SERUM CA19-9 IN PATIENTS WITH PANCREATIC CANCER / 解放军医学杂志

This study was conducted to assess the diagnostic value of serum CA19 9 in patients with pancreatic cancer. Seven hundred and seventy eight patients with the diagnosis of pancreatic cancer were involved in the study, and every patient had serum CA19 9 determined. The descriptive statistics and correlation analysis were used to evaluate the serum CA19 9 as an index in patients with pancreatic cancer. Results showed that 80 33% patients had the serum CA19 9 value higher than 37U/ml. Further more, a positive correlation was found between the serum CA19 9 and the TNM status of pancreatic cancer( r =0 513, P