ABSTRACT
Introducción. El objetivo del presente estudio es determinar la asociación entre desempleo y suicidio e investigar si existen factores relacionados con el ciclo económico o sociodemográficos que influyan sobre la citada asociación. Métodos. Realizamos un análisis de tendencias temporales para estudiar los cambios habidos en España en el número de suicidios entre 1999 y 2013. Utilizamos el coeficiente de correlación de Pearson y modelos de regresión para valorar la asociación entre desempleo y suicidio. Resultados. Encontramos una asociación positiva entre desempleo y suicidio en el periodo previo a la crisis en hombres. En ese periodo (1999-2007), en la población total, cada incremento del 1% en la variación anual de desempleo se asoció a un 6,90% de incremento en la variación anual de suicidio. En hombres en edad laboral, el 1% de variación anual de desempleo se asoció a un 9,04% de incremento en la variación anual de suicidio. Conclusiones. La correlación entre desempleo y suicidio es relevante en periodos de estabilidad económica, y más débil durante la reciente crisis económica. Desempleo y suicidio tienen una relación compleja, modulada por la edad, el sexo y el ciclo económico (AU)
Introduction. The aim of the present work is to determine the association between unemployment and suicide, and to investigate whether this association is affected by changes in the economic cycle or other variables such as age and sex. Methods. A time-trend analysis was conducted to study changes in the number of suicides between 1999 and 2013 in Spain. Pearson's correlation coefficients and regression models were used to find the association between unemployment and suicide. Results. A significant positive association was found between unemployment and suicide in the pre-crisis period in men. In that period (1999-2007), each 1% annual increase in unemployment was associated with a 6.90% increase in the annual variation of suicide in the total population, and with a 9.04% increase in the annual variation of suicide in working age men. Conclusions. The correlation between unemployment and suicide is significant in periods of economic stability, but has weakened during the recent financial crisis. Unemployment and suicide have a complex relationship modulated by age, sex and economic cycle (AU)
Subject(s)
Humans , Male , Female , Economic Recession/statistics & numerical data , Suicide/economics , Suicide/prevention & control , Unemployment , Social Support , Epidemiological Monitoring , Spain/epidemiology , Logistic Models , Mental Health , Occupational Health , Linear Models , Models, Theoretical/methods , Models, Theoretical/statistics & numerical dataABSTRACT
El objetivo de este trabajo es crear ecuaciones que estimen las medidas de los pliegues cutáneos para escolares de 6 a 13 años de edad. Como resultado se obtuvieron catorce ecuaciones que estiman algunos pliegues cutáneos. Las ecuaciones se validaron con muestras aleatorias de 479 niñas y 541 niños del estado de Puebla y otras 2 muestras aleatorias del estado de Veracruz con 155 niñas y 146 niños respectivamente; las mediciones directas se realizaron con la metodología y unidades ISAK (International Society for the Advancement of Kinanthropometry) (AU)
The aim of this paper is to create equations that predict the skinfold measures for school children 6 to 13 years old. Fourteen resulting equations were derived to estimate some measures of skinfold. The equations were validated with random samples of 479 girls and 541 boys in the state of Puebla and 2 other random samples of the state of Veracruz with 155 girls and 146 boys respectively; direct measurements were performed with the methodology and units ISAK (International Society for the Advancement of Kinanthropometry (AU)
Subject(s)
Humans , Male , Female , Child , Adolescent , Skinfold Thickness , Physical Education and Training/methods , Models, Theoretical/methods , Anthropometry/instrumentation , Child Development/physiology , Body Weights and Measures , Regression Analysis , Weight by Height/physiology , 28599 , Statistics, NonparametricABSTRACT
Objetivos: demostrar mediante la teoría de la decisión que el cribado bioquímico-ecográfico del síndrome de Down no debe aplicarse de forma universal sino teniendo en cuenta los umbrales de decisión. Desarrollar el cálculo matemático individualizado para cada gestante de los umbrales de decisión siguiendo el modelo de Pauker-Kassirer. Implementar un método simple para la obtención individualizada de las utilidades que intervienen. Material y métodos: definimos un diagrama de influencia con: variables aleatorias: tener Síndrome de Down, resultado del cribado, pérdida gestacional tras amniocentesis. Decisiones: aplicar el cribado, realizar amniocentesis. Utilidades relativas a los diferentes resultados posibles calculadas en un grupo de 10 gestantes consecutivas mediante diagramas de equivalencia temporal para el cálculo del tiempo de vida ajustado en calidad. Realizamos un análisis de sensibilidad comparando la utilidad de cada estrategia en función de la probabilidad a priori. Los cálculos fueron realizados con OpenMarkov (http://www.openmarkov.org). Resultados: con las utilidades obtenidas (tener un hijo sano 1; tener un hijo con síndrome de Down 0,57; interrumpir el embarazo por diagnóstico de síndrome de Down 0,90; pérdida gestacional secundaria a amniocentesis 0,80) en gestantes con una probabilidad a priori mayor de 0,014 (Odds de 1/70, corresponde al riesgo de una gestante de 41 años) se obtiene la máxima utilidad realizando directamente una amniocentesis. Al resto deberemos aplicar el cribado porque el umbral diagnóstico (0,0002) es menor que el riesgo en las gestantes más jóvenes. Discusión: la gran variabilidad interindividual de las utilidades aconseja que el cálculo de los umbrales de decisión se individualicen para cada gestante; para ello proponemos un método matemático basado en Pauker-Kassirer (AU)
Objectives: To evaluate by decision making if biochemical and ultrasonographic universal screening of Down syndrome is accurate, or they must be used in a selective way related to decision thresholds. To develope a probabilistic model to calcule the decision thresholds following Pauker-Kassirer model. To design a method of utility assessment to quantify women´s individual preferences. Material and methods: An influence diagram with uncertainty nodes (affected or unaffected birth, positive or negative screening, amniocentesis related miscarriage or no complicated technique), decision nodes (to perform screening, to perform amniocentesis) and utilities was developed. Utilities were the average of 10 consecutive pregnant women preference measures using the time trade-off model to obtain quality-adjusted life years. A sensitivity analysis comparing utility for every strategy related to prior probability was done. To perform mathematical results the free software programme OpenMarkov (http://www.openmarkov.org) was used. Results: Utilities were: unaffected birth 1, Down syndrome-affected birth 0.57, elective abortion after Down syndrome diagnosis 0.9 and amniocentesis procedure related miscarriage 0.8. Over 41 year-old risk (Odds 1/70) invasive diagnostic testing has the maximum expected utility. The testing threshold is lower than the lowest-risk women. Therefore, screening is the best option under that prior probability. Discussion: We agree with prior published data: current cutoff is not appropriate because it assumes that women value equally burdensome procedure-related miscarriage of a normal fetus and Down syndrome-affected birth. There was a substantial subject-to-subject variation; individual preferences should be used to stablish a personalised cutoff following Pauker-Kassirer model (AU)
Subject(s)
Humans , Female , Pregnancy , Decision Theory , Down Syndrome/diagnosis , Down Syndrome/prevention & control , Health Status , Quality of Life , Decision Trees , Mass Screening/prevention & control , Mass Screening/statistics & numerical data , Models, Theoretical/methods , Amniocentesis/trendsABSTRACT
Threshold parameters have distinct referents across models for ordered responses. In difference models, thresholds are trait levels at which responding beyond category k is as likely as responding at or below it; in divide-by-total models, thresholds are trait levels at which responding in category k is as likely as responding in category k - 1. Thus, thresholds in divide-by-total models (but not in difference models) are the crossings of the option response functions for consecutive categories. Thresholds in difference models are always ordered but they may inconsequentially yield ordered or disordered crossings. In contrast, assimilation of thresholds and crossings in divide-by-total models questions category order when crossings are disordered. We analyze these aspects of difference and divide-by-total models, their relation to the order of response categories, and the consequences of collapsing categories to instate ordered crossings under divide-by-total models. We also show that item parameters in models for ordered responses can never contradict the pre-assumed order of categories and that the empirical order can only be established using a polytomous model that does not assume ordered categories, although this often gives rise to spurious outcomes. Practical implications for scale development are discussed (AU)
No disponible
Subject(s)
Humans , Male , Female , Models, Psychological , Psychometrics/methods , Psychometrics/trends , Psychological Theory , Psychiatric Status Rating Scales/statistics & numerical data , Psychiatric Status Rating Scales/standards , Models, Theoretical/methods , Surveys and Questionnaires , Algorithms , Factor Analysis, StatisticalABSTRACT
No disponible
Subject(s)
Humans , Male , Female , Meditation/psychology , Confidence Intervals , Psychometrics/methods , Psychometrics/organization & administration , Psychometrics/standards , Mindfulness/methods , Mindfulness/organization & administration , Mindfulness/standards , Models, Theoretical/methods , Models, Theoretical/prevention & control , Conscience , 28599ABSTRACT
OBJECTIVES: Wheezing is a very common problem in infants in the first months of life. The objective of this study is to identify risk factors that may be acted upon in order to modify the evolution of recurrent wheezing in the first months of life, and to develop a model based on certain factors associated to recurrent wheezing in nursing infants capable of predicting the probability of developing recurrent wheezing in the first year of life. METHODS: The sample was drawn from a cross-sectional, multicentre, descriptive epidemiological study based on the general population. A total of 1164 children were studied, corresponding to a questionnaire response rate of 71%. The questionnaire of the Estudio Internacional de Sibilancias en Lactantes (EISL) was used. Multiple logistic regression analysis was used to estimate the probability of developing recurrent wheezing and to quantify the contribution of each individual variable in the presence of the rest. RESULTS: Infants presenting eczema and attending nursery school, with a mother who has asthma, smoked during the third trimester of pregnancy, and did not consume a Mediterranean diet during pregnancy were found to have a probability of 79.7% of developing recurrent wheezing in the first year of life. In contrast, infants with none of these factors were seen to have a probability of only 4.1% of developing recurrent wheezing in the first year of life. These results in turn varied according to modifications in the risk or protective factors. CONCLUSIONS: The mathematical model estimated the probability of developing recurrent wheezing in infants under one year of age in the province of Salamanca (Spain), according to the risk or protective factors associated to recurrent wheezing to which the infants are or have been exposed
No disponible
Subject(s)
Humans , Male , Female , Infant , Models, Theoretical/methods , Models, Theoretical/policies , Respiratory Sounds/diagnosis , Respiratory Sounds/immunology , Risk Factors , Asthma/complications , Asthma/diagnosis , Models, Theoretical/statistics & numerical data , Surveys and QuestionnairesABSTRACT
No disponible
Subject(s)
Humans , Male , Female , Measures of Association, Exposure, Risk or Outcome , Anthropology, Cultural/legislation & jurisprudence , Violence/legislation & jurisprudence , Domestic Violence/legislation & jurisprudence , Forensic Medicine/legislation & jurisprudence , Qualitative Research , Odds Ratio , Confidence Intervals , Models, Theoretical/legislation & jurisprudence , Models, Theoretical/methods , Intimate Partner Violence/legislation & jurisprudenceABSTRACT
Two experiments evaluated the impact of different deviations from golden proportion on subjective perception of beauty. Black and white adaptations of Mondrian paintings modified to fit golden, 1/6 and 1/2 proportions were used as stimuli. Within each trial, participants were exposed to two versions of the same painting on a computer screen. Participants were given 1500 ms to select the one they considered more beautiful. In experimental trials one of the paintings presented the golden proportion while the other presented either the 1/2 or the1/6 proportion. The two paintings were identical in control trials. University students without formal training in art showed preference for golden ratio stimuli over 1/6 stimuli, but not over 1/2 stimuli, both, when they were tested in within-subject (Experiment 1) and betweensubject (Experiment 2) designs (AU)
En dos experimentos se evaluó el impacto de distintas desviaciones de la proporción áurea sobre la percepción de la belleza. Como estímulos se utilizaron adaptaciones en blanco y negro de pinturas de Mondrian ajustadas a la proporciones áurea, 1/6 y 1/2. En cada ensayo se presentaron a los participantes dos versiones del mismo estímulo. Los participantes dispusieron de 1500 ms para seleccionar el estímulo que consideraban más bello. En los ensayos experimentales una de las pinturas mantuvo la proporción áurea, mientras que la otra se ajustó a la proporción 1/2 ó 1/6. En los ensayos de control las proporciones de los estímulos fueron idénticas. Los participantes, estudiantes universitarios sin formación en arte, seleccionaron como más bellos los estímulos con proporción áurea en comparación con la proporción 1/6, pero no en comparación con la proporción 1/2. Estos resultados fueron consistentes tanto con un diseño intrasujeto (Experimento 1) como en un diseño entregrupos (Experimento 2) (AU)
Subject(s)
Humans , Male , Female , Adult , Beauty , Psychology, Experimental/methods , Psychology, Experimental/trends , Students/psychology , Models, Theoretical/methods , Data Analysis/methods , Data Analysis/statistics & numerical data , Analysis of VarianceABSTRACT
BACKGROUND: Accurate assessment of the depth of tumor invasion (DI) in microinvasive squamous cell carcinoma (MISCC) of the tongue is critical to prognosis. An arithmetic model is generated to determine a reliable method of measurement of DI and correlate this with the local recurrence. MATERIAL AND METHODS: Tumor thickness (TT) and DI were measured in tissue sections of 14 cases of MISCC of the tongue, by manual ocular micrometer and digital image analysis at four reference points (A, B, C, and D). The comparison of TT and DI with relevant clinicopathologic parameters was assessed using Mann Whitney U test. Reliability of these methods and the values obtained were compared and correlated with the recurrence of tumors by Wilcoxon Signed Ranks Test. 3D reconstruction of the lesion was done on a Cartesian coordinate system. X face was on the YZ plane and Z face was on the XY plane of the coordinate system. RESULTS: Computer generated 3D model of oral mucosa in four cases that recurred showed increased DI in the Z coordinate compared to the XY coordinate. The median DI measurements between XY and Z coordinates in these cases showed no significant difference (Wilcoxon Signed Ranks Test, p = 0.068). CONCLUSIONS: The assessment of DI in 3 dimensions is critical for accurate assessment of MISCC and precise DI allows complete removal of tumor
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Carcinoma, Squamous Cell , Tongue Neoplasms/pathology , Tongue Neoplasms , Carcinoma, Squamous Cell/pathology , Prognosis , Imaging, Three-Dimensional/instrumentation , Imaging, Three-Dimensional/methods , Imaging, Three-Dimensional , Models, Theoretical/methods , Neoplasm Recurrence, Local/complications , Neoplasm Recurrence, Local/diagnosis , Mouth Mucosa/pathology , Mouth Mucosa , Image Processing, Computer-Assisted/instrumentation , Image Processing, Computer-Assisted/methods , Image Processing, Computer-AssistedABSTRACT
BACKGROUND: Although there is a broad consensus on the use of statistical procedures for mediation analysis in psychological research, the interpretation of the effect of mediation is highly controversial because of the potential violation of the assumptions required in application, most of which are ignored in practice. METHOD: This paper summarises two currently independent procedures for mediation analysis, the classical/SEM and causal inference/CI approaches, together with the statistical assumptions required to estimate unbiased mediation effects, in particular the existence of omitted variables or confounders. A simulation study was run to test whether violating the assumptions changes the estimation of mediating effects. RESULTS: The simulation study showed a significant overestimation of mediation effects with latent confounders. CONCLUSIONS: We recommend expanding the classical with the causal inference approach, which generalises the results of the first approach to mediation using a common estimation method and incorporates new tools to evaluate the statistical assumptions. To achieve this goal, we compare the distinguishing features of recently developed software programs in R, SAS, SPSS, STATA and Mplus
ANTECEDENTES: aunque existe un amplio consenso en el uso de los procedimientos estadísticos para el análisis de la mediación en la investigación psicológica, la interpretación del efecto de mediación resulta muy controvertida debido al potencial incumplimiento de los supuestos que requiere su aplicación, la mayoría de los cuales son ignorados en la práctica. MÉTODO: se resumen los procedimientos actualmente vigentes para el análisis de mediación desde los enfoques clásico y de la inferencia causal, junto con los supuestos estadísticos para estimar efectos de mediación no sesgados, en particular la existencia de variables omitidas o confundidores, y se utiliza un estudio de simulación para determinar si la violación de los supuestos puede cambiar la estimación del efecto de mediación. RESULTADOS: el estudio de simulación mostró una sobreestimación importante del efecto de mediación en presencia de confundidores latentes. CONCLUSIONES: se recomienda complementar el enfoque clásico con el enfoque de la inferencia causal, que generaliza los resultados del primer enfoque al análisis de la mediación e incorpora nuevas herramientas para evaluar sus supuestos estadísticos. Para alcanzar tal objetivo se comparan las características distintivas de los programas de software recientemente desarrollados en R, SAS, SPSS y Mplus
Subject(s)
Humans , Male , Female , Negotiating/methods , Negotiating/psychology , Psychoanalytic Interpretation , Models, Psychological , Models, Theoretical/methods , Models, Theoretical/statistics & numerical data , Statistics as Topic/instrumentation , Statistics as Topic/methods , Data Interpretation, Statistical , Research/instrumentation , Research/statistics & numerical data , Models, Statistical , Cohort StudiesABSTRACT
El presente trabajo muestra qué información debe recogerse para realizar el análisis funcional de un caso clínico, qué características debe poseer dicha información, cómo pueden integrarse los datos disponibles y cómo se pueden representar gráficamente los juicios clínicos para que ayuden en la elección del tratamiento. El análisis funcional consiste en la integración de variables y relaciones causales con los problemas del cliente y con los objetivos del tratamiento. Presentamos un caso práctico ilustrativo de evaluación conductual, de integración en un análisis funcional de los datos obtenidos y de su representación gráfica mediante un diagrama causal. El análisis funcional y su representación gráfica se presentan de forma que sirvan para comunicar con claridad el análisis funcional a otras personas, para enseñar a formular casos clínicos y para elegir el mejor enfoque para el tratamiento. El análisis funcional es dinámico, hipotético e idiográfico y su validez puede restringirse a determinadas situaciones o contextos (AU)
This article reviews what information needs to be gathered to carry out the functional analysis of a clinical case, what the scientific characteristics of this information are, how to integrate available information, and how to graphically represent clinical judgments to make treatment decisions. Functional analysis is the integration of important, modifiable, causal variables and causal relations associated with a client´s behavior problems and intervention goals. We present a clinical case to illustrate the applications of behavioral assessment methods and to show how data obtained in the assessment process can be integrated into a functional analysis. Functional Analytic Clinical Case Diagrams (FACCD), which are causal diagrams of a functional analysis, are also introduced. The functional analysis and FACCD are designed to efficiently communicate the functional analysis to others, as an aid in teaching case formulations, and to assist in selecting the most beneficial intervention focus with a client. The functional analysis is a dynamic, hypothesized, idiographic clinical case formulation. The validity of a functional analysis can be confined to particular settings or contexts (AU)
Subject(s)
Humans , Data Collection/methods , Medical History Taking/methods , Case Management , Data Analysis/methods , Models, Theoretical/methodsABSTRACT
Background: Criterion-referenced interpretations of tests are highly necessary, which usually involves the difficult task of establishing cut scores. Contrasting with other Item Response Theory (IRT)-based standard setting methods, a non-judgmental approach is proposed in this study, in which Item Characteristic Curve (ICC) transformations lead to the final cut scores. Method: eCat-Listening, a computerized adaptive test for the evaluation of English Listening, was administered to 1,576 participants, and the proposed standard setting method was applied to classify them into the performance standards of the Common European Framework of Reference for Languages (CEFR). Results: The results showed a classification closely related to relevant external measures of the English language domain, according to the CEFR. Conclusions: It is concluded that the proposed method is a practical and valid standard setting alternative for IRT-based tests interpretations (AU)
Antecedentes: las interpretaciones de los tests referidas a criterio son muy necesarias, lo cual normalmente implica la difícil tarea de establecer puntos de corte. En contraste con otros métodos de standard setting basados en la Teoría de la Respuesta al Ítem (TRI), en este estudio se propone una aproximación no basada en juicios, en que transformaciones de las Curvas Características de los Ítems (CCIs) dan lugar a los puntos de corte finales. Método: se administró eCat-Listening, un test adaptativo informatizado de evaluación de la comprensión oral del inglés, a 1.576 participantes y se aplicó el método de standard setting propuesto para clasificarles en los estándares de ejecución del Marco Común Europeo de Referencia para las lenguas (MCER). Resultados: los resultados mostraron una clasificación estrechamente relacionada con variables externas relevantes sobre dominio del inglés, de acuerdo con el MCER. Conclusiones: se concluye que el método de standard setting propuesto es una alternativa práctica y válida para las interpretaciones de tests basados en TRI (AU)
Subject(s)
Humans , Male , Female , Psychological Tests/statistics & numerical data , Psychological Tests/standards , Research/methods , Psychoanalytic Interpretation , Psychometrics/organization & administration , Psychometrics/standards , Information Services/trends , Information Services , Models, Theoretical/methods , Psychometrics/methods , Psychometrics/statistics & numerical dataABSTRACT
Es de indudable importancia dotar al gestor sanitario de herramientas que permitan predecir el comportamiento de la propagación de una enfermedad infecciosa, de manera que a partir de las mismas se pueden establecer y simular estrategias de control. El desarrollo de tales herramientas es de carácter pluridisciplinar siendo la base de las mismas, algoritmos o modelos matemáticos que son implementados computacionalmente. En este trabajo se muestra el funcionamiento de estos modelos matemáticos y se detalla su clasificación atendiendo a diferentes factores. Además se lleva a cabo un estudio cuantitativo de los mismos haciendo uso de las principales bases de datos relacionadas con el tema de estudio (Medline y Web of Science). De este trabajo se concluye el importante papel que pueden jugar los modelos matemáticos a la hora de simular los procesos infecciosos y, asimismo, se proponen futuras y eficaces vías de investigación en la modelización matemática de enfermedades infecciosas(AU)
This work deals with the study of the use of mathematical models to simulate the spreading of infectious diseases. There is no doubt about the importance of the use of computational tools that allow the health staff to model and predict the spreading of an infectious disease. Using such tools one can establish and simulate disease control strategies. The development of such technologies is a multidisciplinary issue; in this sense, the mathematical algorithms that must be computationally implemented- play a central role. The main goal of this work is to highlight among health community the increasing importance of the use of mathematical models for epidemic disease spreading. Consequently, the main features of such models are introduced and their classification is stated taking into account the behavior, the basic population unit or the mathematical objects used. An exhaustive search of related papers through the most important databases (Medline and Web of Science) are performed. The main conclusion obtained from this work is the central role that mathematical models can play in the simulation of epidemic spreading; moreover, some ideas about the future research are stated(AU)
Subject(s)
Humans , Male , Female , Communicable Diseases/drug therapy , Preventive Medicine/methods , Models, Theoretical/methods , Models, Theoretical/prevention & control , Preventive Health Services , Communicable Diseases/epidemiology , Mathematics/history , Mathematics/organization & administration , Mathematics/standards , Stochastic ProcessesABSTRACT
Background: With the 2-way mixed model, one a fixed factor and the other random, the procedure followed to test statistical significance of the random factor has been the focus of a heated controversy in theoretical and applied statistics, and the debating continues even now. One of the main consequences of this controversy is that the position defended in the classical ANOVA texts on the hypothesis of the significance of the random effect is not the same as that defended in almost all of the professional statistical software programs. Method: In this paper, we deal with a detailed analysis about the controversy of mixed model and the decision about one of two basic options, the non restrictive and the restrictive model. Results: Three key questions we consider to go beyond the controversy are: (1) the two classical models are equivalent, (2) the marginality principle do not allow to test main effects in presence of interactive significant effects and (3) the relevance of linear mixed approach to analyze models with fixed and random effects. Conclusions: We propose the simple solution of using the mixed linear approach with REML estimation instead of the classical linear approach, which is really unapplicable in this context (AU)
Antecedentes: en el modelo mixto de dos factores, con un factor fijo y el otro aleatorio, la forma de probar la significación del factor aleatorio ha sido objeto de una enconada controversia en la estadística teórica y aplicada que todavía hoy sigue siendo objeto de polémica. Una de las consecuencias más sorprendentes de esta controversia es que la posición que se defiende en los textos clásicos de ANOVA sobre la prueba de hipótesis del factor aleatorio no es la misma que la defendida en casi todos los programas estadísticos profesionales. Método: en este trabajo se aborda un análisis detallado de la controversia sobre el modelo mixto y la decisión de adoptar una de las dos opciones básicas, el modelo no restrictivo o el modelo restrictivo. Resultados: las cuestiones clave que se consideran para trascender esta controversia son: (1) las dos opciones básicas son matemáticamente equivalentes, (2) el principio de marginalidad no permite probar efectos principales en presencia de efectos interactivos significativos y (3) la pertinencia del enfoque lineal mixto para analizar modelos con efectos fijos y aleatorios. Discusión: en este trabajo se propone como solución a la controversia la utilización del enfoque lineal mixto con estimación REML en menoscabo del enfoque lineal clásico, que resulta inaplicable en este contexto (AU)
Subject(s)
Humans , Male , Female , Models, Psychological , Models, Theoretical/methods , Models, Theoretical/statistics & numerical data , Analysis of VarianceABSTRACT
El funcionamiento y el rendimiento de los grupos en contextos diferentes están relacionados con el grado en que las características de los miembros son complementarias o suplementarias. El presente artículo describe un procedimiento para cuantificar el grado de disimilitud a nivel de grupo. A diferencia de la mayoría de técnicas existentes, el procedimiento que aquí se describe está normalizado y es invariante a los cambios de localización y escala. Por lo tanto, es posible comparar la disimilitud en escalas con diferente métrica y en grupos de distinto tamaño. La disimilitud está medida en términos relativos, independientemente de la posición que ocupan los individuos en la dimensión que mide la escala. Cuando no existe una justificación teórica para combinar las diversas propiedades medidas, se puede cuantificar la disimilitud para cada escala por separado. También es posible obtener las contribuciones diádicas e individuales respecto a la diversidad global y la asignada a cada escala. Las medidas descriptivas pueden ser complementadas con la significación estadística para, así, comparar los resultados obtenidos con distribuciones discretas de referencia, ya sean simétricas o asimétricas. Se ha elaborado un paquete en R que permite obtener los índices descriptivos y los valores p, además de contener las expresiones desarrolladas para simular una amplia variedad de distribuciones discretas de probabilidad(AU)
Group functioning and performance in different contexts is related to the extent to which group members are complementary or supplementary in terms of psychological attributes. This paper describes a procedure for quantifying the degree of dissimilarity at group level. Unlike most existing techniques the one described here is normalized and is both location and scale invariant, thereby making it suitable for comparing dissimilarity on interval and ratio scales with different ranges and in groups of different sizes. Dissimilarity is measured in relative terms regardless of the exact place on the scale at which individuals are located. When a combination of several scales is not theoretically justified, the dissimilarity for each scale can be quantified. Additionally, dyadic and individual contributions to either the global or scale index can be obtained. The descriptive measures are complemented by statistical significance values in order to compare the results obtained with several discrete distributions of reference, both symmetrical and skewed, which can be specified using the expressions developed. The information that can be provided by the indices and the p values - both obtainable through an R package - is illustrated using data from an empirical study (AU)
Subject(s)
Humans , Male , Female , Codependency, Psychological/physiology , Psychiatric Status Rating Scales/statistics & numerical data , Psychiatric Status Rating Scales/standards , Psychology, Social/instrumentation , Psychology, Social/methods , Psychology, Social/statistics & numerical data , Extraversion, Psychological , Psychometrics/methods , Psychometrics/statistics & numerical data , Interpersonal Relations , Models, Theoretical/methods , Models, Theoretical/statistics & numerical data , Psychology, Social/organization & administration , Psychology, Social/standards , Psychology, Social/trendsABSTRACT
This paper introduces a two-dimensional Item Response Theory (IRT) model to deal with nonignorable nonresponses in tests with dichotomous items. One dimension provides information about the omitting behavior, while the other dimension is related to the persons ability. The idea of embedding an IRT model for missingness into the measurement model is not new but, differently from the existing literature, the model presented in this paper belongs to the Rasch family of models. As a member of the exponential family, the model offers several advantages, such as existence of non trivial sufficient statistics and possibility of specific objective parameter estimation; feasibility of conditional inference; goodness of fit analysis via conditional likelihood ratio tests. Maximum likelihood estimation is discussed, and the applicability of the proposed model is illustrated by using a real data set(AU)
Subject(s)
Humans , Male , Female , Models, Theoretical/methods , Psychoanalytic Theory , Psychological Theory , Psychology, Experimental/methods , Psychology, Experimental/trends , Models, Statistical , 51840/methodsABSTRACT
The a priori determination of a proper sample size necessary to achieve some specified power is an important problem encountered frequently in practical studies. To establish the needed sample size for a two-sample t test, researchers may conduct the power analysis by specifying scientifically important values as the underlying population means while using a variance estimate obtained from related research or pilot study. In order to take account of the variability of sample variance, this article considers two approaches to sample size determinations. One provides the sample size required to guarantee with a given assurance probability that the actual power exceeds the planned power. The other gives the necessary sample size such that the expected power attains the designated power level. The suggested paradigm of adjusted sample variance combines the existing procedures into one unified framework. Numerical results are presented to illustrate the usefulness and advantages of the proposed approaches that accommodate the stochastic nature of the sample variance. More importantly, supplementary computer programs are developed to aid the usefulness and implementation of the suggested techniques. The exposition helps to clarify discrepancy in the previous demonstration and to extend the development of sample size methodology(AU)
Subject(s)
Humans , Male , Female , Models, Theoretical/methods , Models, Theoretical/statistics & numerical data , Psychology, Experimental/methods , Psychology, Experimental/statistics & numerical data , Behavior/physiology , Behavior Therapy/statistics & numerical data , Behavioral Sciences/methods , Behavioral Sciences/statistics & numerical data , Mathematical Computing , Analysis of Variance , 28599 , Psychology, Experimental/organization & administration , Psychology, Experimental/standards , Psychology, Experimental/trendsABSTRACT
The application of mean and covariance structure analysis with quantitative data is increasing. However, latent means analysis with qualitative data is not as widespread. This article summarizes the procedures to conduct an analysis of latent means of dichotomous data from an item response theory approach. We illustrate the implementation of these procedures in an empirical example referring to the organizational context, where a multi-group analysis was conducted to compare the latent means of three employee groups in two factors measuring personal preferences and the perceived degree of rewards from the organization. Results show that higher personal motivations are associated with higher perceived importance of the organization, and that these perceptions differ across groups, so that higher-level employees have a lower level of personal and perceived motivation. The article shows how to estimate the factor means and the factor correlation from dichotomous data, and how to assess goodness of fi t. Lastly, we provide the M-Plus syntax code in order to facilitate the latent means analyses for applied researchers (AU)
La aplicación de modelos de análisis de estructura de medias y covarianzas en datos cuantitativos está extendiéndose. Sin embargo, el análisis de medias latentes a partir de datos cualitativos es menos habitual. Este artículo resume los procedimientos para llevar a cabo un análisis de estructura de medias latentes con ítems dicotómicos desde un enfoque de la teoría de respuesta al ítem. Se ilustra la implementación de dichos procedimientos en un ejemplo con datos empíricos referidos al contexto organizacional, donde se lleva a cabo un análisis multi-grupo para comparar las medias latentes de tres grupos de empleados en dos factores que miden preferencias personales y el grado percibido en que la organización las refuerza. Los resultados indican que a mayor motivación personal, se necesita mayor refuerzo por parte de la organización, y que existen diferencias entre grupos, ocurriendo que los empleados que ocupan posiciones más altas tienen menor nivel de motivaciones personales y organizacionales. El artículo muestra cómo estimar las medias y correlaciones de los factores de ítems dicotómicos, y cómo evaluar la bondad de ajuste. Por último, se muestra la sintaxis M-Plus para facilitar la aplicación de este tipo de análisis a los investigadores AU)
Subject(s)
Humans , Male , Female , Organizations/organization & administration , Organizations/standards , Psychology, Industrial/methods , Psychology, Industrial/trends , Psychology, Applied/methods , Psychology, Applied/trends , Analysis of Variance , Surveys and Questionnaires , Models, Theoretical/methods , 28599ABSTRACT
Objetivo. Valorar la utilidad del modelo matemático Data Envelopment Analysis (DEA) para medir la eficiencia de programas de tratamiento con opiáceos (PTO). Material y métodos. Se realiza un estudio de "simulación", es decir, se parte de un conjunto de supuestos y se manejan datos no reales pero fundamentados en la literatura. Se comparan 15 hipotéticos PTO y se mide la eficiencia de cada uno de ellos. De cada programa habríamos obtenido información sobre seis variables, tres de las cuales serían consideradas como indicadores de input (ratio terapeuta/paciente, unidades asistenciales en drogodependencias y porcentaje de pacientes con dosis adecuadas) y tres de output (días de abstinencia de heroína en el último mes, tasas de retención y grado de mejoría de los problemas relacionados con el consumo). La matriz de datos generada se somete a análisis mediante el DEA. Resultados. El modelo ordena los programas en función de su nivel de eficiencia. Los programas P8, P9, P11, P5 y P6 son considerados "ineficientes" y se estiman las magnitudes de las variables de input y output que distan de un rendimiento óptimo. En este análisis, la variable de output que añade más eficiencia a los programas es el "número de días de abstinencia de heroína en el último mes" y la variable de input que añade más ineficiencia a los mismos, es el "porcentaje de pacientes con dosis adecuadas". Conclusión. El modelo DEA tiene una utilidad potencial para la medida comparativa de la eficiencia de PTO. La información aportada por este modelo podría ser utilizada por los coordinadores de programas para introducir cambios en los procesos terapéuticos con el objetivo de mejorar la calidad asistencial (AU)
Aim. To assess the usefulness of the mathematical model Data Envelopment Analysis (DEA) to measure the efficiency of opioid substitution programs (OSP). Material and Methods. A simulation study was conducted based on a series of assumptions that are tested using non-real data imputed from theoretical background. Fifteen hypothetical OSP are compared to estimate their relative efficiency. We obtained six variables from each program, three of which are considered input indices (therapists/patients ratio, number of treatment units and proportion of patients with adequate opioid doses), and the other three are considered output indices (number days of heroin abstinence in the last month, retention rates and degree of recovery from drug-use related problems). The data set was subjected to DEA analyses. Results. The DEA model ranked the OSP as a function of their efficiency levels. Programs P8, P9, P11, P5 and P6 were considered inefficient and the magnitude of the input and output variables were far from optimal achievement. In these analyses, the output variable that yielding a greater efficiency was the number days of heroin abstinence in the last month and the input variable providing greater inefficiency was the proportion of patients with adequate opioid doses. Conclusion. The DEA model yields can be useful to measure the relative efficiency of the OSP. The information provided by the model may be used by OSPs managers to introduce changes in therapeutic processes with the aim of increasing their quality (AU)
Subject(s)
Humans , Male , Female , Opiate Substitution Treatment/methods , Opioid-Related Disorders/diagnosis , Opioid-Related Disorders/drug therapy , Buprenorphine/therapeutic use , Models, Theoretical/methods , Models, Theoretical/prevention & control , Opioid-Related Disorders/epidemiology , Models, Theoretical/statistics & numerical data , Teaching Care Integration Services/trendsABSTRACT
La resistencia a los antimicrobianos es uno de los principales problemas a los que se enfrenta la comunidad sanitaria internacional. El estudio de la resistencia se debe realizar desde un enfoque pluridisciplinar y en este sentido se analiza el papel que puede jugar la Modelización Matemática en este escenario. Así se realiza un análisis tanto cuantitativo como cualitativo de los trabajos que han aparecido en la literatura científica mediante una búsqueda en las principales bases de datos: MEDLINE, SCOPUS e ISI Web of Science. Tras el análisis realizado en este estudio se observa que son pocos los trabajos relacionados con la temática objeto de estudio pero han sido publicados en revistas de un alto impacto; asimismo podemos afirmar que el desarrollo de modelos matemáticos puede jugar un papel muy importante a la hora de analizar y estudiar tanto los tratamientos para prevenir la aparición de las resistencias como el establecimiento y evaluación de estrategias de control en ambientes hospitalarios y la predicción del comportamiento de las infecciones por cepas resistentes(AU)
The antibiotic resistance is one of the greatest challenges of the international health community. The study of antibiotic resistance must be a multidisciplinary task and, in this sense, the main goal of this work is to analyze the role that Mathematical Modeling can play in this scenario. A qualitative and cuantitative analysis of the works published in the scientific literature is done by means of a search in the most important databases: MEDLINE, SCOPUS and ISI Web of Science. Consequently, there are few papers related to our topic but the existing works have been published in high-quality and impact international journals. Moreover, we can state that mathematical models are a very important and useful tool to analyze and study both the treatments protocols for resistance prevention and the assesment of control strategies in hospital environtment, or the prediction of the evolution of diseases due to resistant strains(AU)