964 resultados para t-statistic
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The situational and interpersonal characteristics of homicides occurring in Houston, Texas, during 1987 were investigated. A total of 328 cases were ascertained from the linking of police computer data, medical examiner's records, and death certificate information. The medical examiner's records contained all of the ascertained cases. The comparability ratio between the medical examiner's records and police and vital statistic data was 1.03 and 0.966, respectively. Data inconsistencies were found between the three information sources on Spanish surname, age, race/ethnicity, external cause of death coding, alcohol and drug involvement, weapon/method used, and Hispanic immigration status. Recommendations for improving the quality of homicide information gathered and for linking homicide surveillance systems were made.^ Males constituted 82% of all victims. The age-adjusted homicide rate for Blacks was 31.1 per 100,000 population, for Hispanics 19.2, and for Anglos 5.4. Among males, Blacks had an age-adjusted rate of 54.5, Hispanics, 31.0, and Anglos 7.5. Among females, Blacks had an age-adjusted rate of 9.3, Hispanics 6.1, and Anglos 3.1. Black males, ages 25-34, had the highest homicide rate, at 96.5.^ Half of all homicides occurred in a residence. Among Hispanic males, homicides occurred most often in the street. Firearms were used to commit 64% of the homicides. Arguments preceded 58% of all cases. Nearly two-thirds of the victims knew their assailant. Only 15% of males compared to 62% of females were killed by a spouse, an intimate acquaintance, or a family member. Blacks (93%) and Hispanics (88%) were more likely than Anglos (70%) to have been killed by persons of the same race/ethnicity. Nearly three-fourths of all Houston Hispanic homicide victims were foreign born.^ Alcohol was detected in 47% of the victims tested. Nearly one-third of those tested had blood alcohol concentrations (BACs) greater than 100 mg%. Males (53%) were more likely than females (20%) to have positive BACs. Hispanic males (64%) were more likely to have detectable BACs than either Black (51%) or Anglo (44%) males.^ Illegal drugs were detected in 20% of the victims tested. One-fourth of the victims who tested positive for drugs had more than one drug in their system at death. The stimulant cocaine was the most commonly detected drug, comprising 53% of all illegal drugs identified.^ Recommendations for the primary, secondary, and tertiary prevention of homicide and for future homicide research are made. ^
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This study was designed to identify some of the factors related to patterns of physician visits to nursing home residents. The relationship of ten resident and organizational characteristics to patterns of physician visits was investigated through secondary analysis of data abstracted from the 1973-74 National Nursing Home Survey of the National Center for Health Statistics. The study sample was composed of 11,135 of the 19,013 nursing home residents who participated in the survey.^ The analytic results revealed that all ten variables had a statistically significant relationship to patterns of physician visits, mainly due to the large sample size. The degrees of association between the variables, measured by the Cramer's V statistic, ranged from moderate to very weak.^ Certification status of the nursing home under Medicare and/or Medicaid was shown to be most strongly related to patterns of physician visits, followed by primary source of payment for nursing home care, and residence prior to nursing home admission. Several variables thought to be related to patterns of physician visits were found to have a very weak relationship: age of the resident, marital status, length of stay, primary diagnosis, number of chronic conditions, activities of daily living status, and levels of care.^ In order to get a more precise picture of the relative influence of certification status and primary source of payment when the other variables were statistically controlled, these two variables were combined into a single variable. The results revealed that the combined effects of certification status and primary source of payment were sustained, regardless of differences in the residents' personal, utilization, and health status characteristics, and the levels of care that they received. The results also indicated that the five groups created by combining the two variables differed in patterns of physician visits. For example, private pay residents in intermediate care facilities (ICF's) and non-certified facilities were more likely to receive unscheduled visits than private pay residents in skilled nursing homes (SNH's), residents in SNH's supported by Medicare or Medicaid, and residents in ICF's supported by Medicaid. ^
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Objective: In this secondary data analysis, three statistical methodologies were implemented to handle cases with missing data in a motivational interviewing and feedback study. The aim was to evaluate the impact that these methodologies have on the data analysis. ^ Methods: We first evaluated whether the assumption of missing completely at random held for this study. We then proceeded to conduct a secondary data analysis using a mixed linear model to handle missing data with three methodologies (a) complete case analysis, (b) multiple imputation with explicit model containing outcome variables, time, and the interaction of time and treatment, and (c) multiple imputation with explicit model containing outcome variables, time, the interaction of time and treatment, and additional covariates (e.g., age, gender, smoke, years in school, marital status, housing, race/ethnicity, and if participants play on athletic team). Several comparisons were conducted including the following ones: 1) the motivation interviewing with feedback group (MIF) vs. the assessment only group (AO), the motivation interviewing group (MIO) vs. AO, and the intervention of the feedback only group (FBO) vs. AO, 2) MIF vs. FBO, and 3) MIF vs. MIO.^ Results: We first evaluated the patterns of missingness in this study, which indicated that about 13% of participants showed monotone missing patterns, and about 3.5% showed non-monotone missing patterns. Then we evaluated the assumption of missing completely at random by Little's missing completely at random (MCAR) test, in which the Chi-Square test statistic was 167.8 with 125 degrees of freedom, and its associated p-value was p=0.006, which indicated that the data could not be assumed to be missing completely at random. After that, we compared if the three different strategies reached the same results. For the comparison between MIF and AO as well as the comparison between MIF and FBO, only the multiple imputation with additional covariates by uncongenial and congenial models reached different results. For the comparison between MIF and MIO, all the methodologies for handling missing values obtained different results. ^ Discussions: The study indicated that, first, missingness was crucial in this study. Second, to understand the assumptions of the model was important since we could not identify if the data were missing at random or missing not at random. Therefore, future researches should focus on exploring more sensitivity analyses under missing not at random assumption.^
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Background. The United Nations' Millennium Development Goal (MDG) 4 aims for a two-thirds reduction in death rates for children under the age of five by 2015. The greatest risk of death is in the first week of life, yet most of these deaths can be prevented by such simple interventions as improved hygiene, exclusive breastfeeding, and thermal care. The percentage of deaths in Nigeria that occur in the first month of life make up 28% of all deaths under five years, a statistic that has remained unchanged despite various child health policies. This paper will address the challenges of reducing the neonatal mortality rate in Nigeria by examining the literature regarding efficacy of home-based, newborn care interventions and policies that have been implemented successfully in India. ^ Methods. I compared similarities and differences between India and Nigeria using qualitative descriptions and available quantitative data of various health indicators. The analysis included identifying policy-related factors and community approaches contributing to India's newborn survival rates. Databases and reference lists of articles were searched for randomized controlled trials of community health worker interventions shown to reduce neonatal mortality rates. ^ Results. While it appears that Nigeria spends more money than India on health per capita ($136 vs. $132, respectively) and as percent GDP (5.8% vs. 4.2%, respectively), it still lags behind India in its neonatal, infant, and under five mortality rates (40 vs. 32 deaths/1000 live births, 88 vs. 48 deaths/1000 live births, 143 vs. 63 deaths/1000 live births, respectively). Both countries have comparably low numbers of healthcare providers. Unlike their counterparts in Nigeria, Indian community health workers receive training on how to deliver postnatal care in the home setting and are monetarily compensated. Gender-related power differences still play a role in the societal structure of both countries. A search of randomized controlled trials of home-based newborn care strategies yielded three relevant articles. Community health workers trained to educate mothers and provide a preventive package of interventions involving clean cord care, thermal care, breastfeeding promotion, and danger sign recognition during multiple postnatal visits in rural India, Bangladesh, and Pakistan reduced neonatal mortality rates by 54%, 34%, and 15–20%, respectively. ^ Conclusion. Access to advanced technology is not necessary to reduce neonatal mortality rates in resource-limited countries. To address the urgency of neonatal mortality, countries with weak health systems need to start at the community level and invest in cost-effective, evidence-based newborn care interventions that utilize available human resources. While more randomized controlled studies are urgently needed, the current available evidence of models of postnatal care provision demonstrates that home-based care and health education provided by community health workers can reduce neonatal mortality rates in the immediate future.^
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In the biomedical studies, the general data structures have been the matched (paired) and unmatched designs. Recently, many researchers are interested in Meta-Analysis to obtain a better understanding from several clinical data of a medical treatment. The hybrid design, which is combined two data structures, may create the fundamental question for statistical methods and the challenges for statistical inferences. The applied methods are depending on the underlying distribution. If the outcomes are normally distributed, we would use the classic paired and two independent sample T-tests on the matched and unmatched cases. If not, we can apply Wilcoxon signed rank and rank sum test on each case. ^ To assess an overall treatment effect on a hybrid design, we can apply the inverse variance weight method used in Meta-Analysis. On the nonparametric case, we can use a test statistic which is combined on two Wilcoxon test statistics. However, these two test statistics are not in same scale. We propose the Hybrid Test Statistic based on the Hodges-Lehmann estimates of the treatment effects, which are medians in the same scale.^ To compare the proposed method, we use the classic meta-analysis T-test statistic on the combined the estimates of the treatment effects from two T-test statistics. Theoretically, the efficiency of two unbiased estimators of a parameter is the ratio of their variances. With the concept of Asymptotic Relative Efficiency (ARE) developed by Pitman, we show ARE of the hybrid test statistic relative to classic meta-analysis T-test statistic using the Hodges-Lemann estimators associated with two test statistics.^ From several simulation studies, we calculate the empirical type I error rate and power of the test statistics. The proposed statistic would provide effective tool to evaluate and understand the treatment effect in various public health studies as well as clinical trials.^
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Background: Little is known about the effects on patient adherence when the same study drug is administered in the same dose in two populations with two different diseases in two different clinical trials. The Minocycline in Rheumatoid Arthritis (MIRA) trial and the NIH Exploratory Trials in Parkinson's disease (NET-PD) Futility Study I provide a unique opportunity to do the above and to compare methods measuring adherence. This study may increase understanding of the influence of disease and adverse events on patient adherence and will provide insights to investigators selecting adherence assessment methods in clinical trials of minocycline and other drugs in future.^ Methods: Minocycline adherence by pill count and the effect of adverse events was compared in the MIRA and NET-PD FS1 trials using multivariable linear regression. Within the MIRA trial, agreement between assay and pill count was compared. The association of adverse events with assay adherence was examined using multivariable logistic regression.^ Results: Adherence derived from pill count in the MIRA and NET-PD FS1 trials did not differ significantly. Adverse events potentially related to minocycline did not appear useful to predict minocycline adherence. In the MIRA trial, adherence measured by pill count appears higher than adherence measured by assay. Agreement between pill count and assay was poor (kappa statistic = 0.25).^ Limitations: Trial and disease are completely confounded and hence the independent effect of disease on adherence to minocycline treatment cannot be studied.^ Conclusion: Simple pill count may be preferred over assay in the minocycline clinical trials to measure adherence. Assays may be less sensitive in a clinical setting where appointments are not scheduled in relation to medication administration time, given assays depend on many pharmacokinetic and instrument-related factors. However, pill count can be manipulated by the patient. Another study suggested that self-report method is more sensitive than pill count method in differentiating adherence from non-adherence. An effect of medication-related adverse events on adherence could not be detected.^
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This thesis project is motivated by the potential problem of using observational data to draw inferences about a causal relationship in observational epidemiology research when controlled randomization is not applicable. Instrumental variable (IV) method is one of the statistical tools to overcome this problem. Mendelian randomization study uses genetic variants as IVs in genetic association study. In this thesis, the IV method, as well as standard logistic and linear regression models, is used to investigate the causal association between risk of pancreatic cancer and the circulating levels of soluble receptor for advanced glycation end-products (sRAGE). Higher levels of serum sRAGE were found to be associated with a lower risk of pancreatic cancer in a previous observational study (255 cases and 485 controls). However, such a novel association may be biased by unknown confounding factors. In a case-control study, we aimed to use the IV approach to confirm or refute this observation in a subset of study subjects for whom the genotyping data were available (178 cases and 177 controls). Two-stage IV method using generalized method of moments-structural mean models (GMM-SMM) was conducted and the relative risk (RR) was calculated. In the first stage analysis, we found that the single nucleotide polymorphism (SNP) rs2070600 of the receptor for advanced glycation end-products (AGER) gene meets all three general assumptions for a genetic IV in examining the causal association between sRAGE and risk of pancreatic cancer. The variant allele of SNP rs2070600 of the AGER gene was associated with lower levels of sRAGE, and it was neither associated with risk of pancreatic cancer, nor with the confounding factors. It was a potential strong IV (F statistic = 29.2). However, in the second stage analysis, the GMM-SMM model failed to converge due to non- concaveness probably because of the small sample size. Therefore, the IV analysis could not support the causality of the association between serum sRAGE levels and risk of pancreatic cancer. Nevertheless, these analyses suggest that rs2070600 was a potentially good genetic IV for testing the causality between the risk of pancreatic cancer and sRAGE levels. A larger sample size is required to conduct a credible IV analysis.^
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Se trata de un primer acercamiento a una posible teoría de la "Imagología regional", aplicada a la imagen de Mendoza obtenida a través de viajeros europeos del siglo XIX A partir de la regionalización de la literatura de viaje propiciada por los historiadores Samuel Trifilo y Edmundo Correas para el contexto mendocino, se desarrolla la perspectiva de una imagen de lo cultural, como contracara de la reducción a la motivación básicamente ideológica de los viajeros sustentada por Mary Louise Pratt.. El análisis de una serie de relatos de viaje a Mendoza permite distinguir para la primera mitad del siglo XIX entre estereotipos positivos (así en Haigh) y negativos (así en Darwin) como "imágenes residuales" (Zamorano de Montiel) referidas a la percepción de lo cultural, tanto puntuales como integradas en una "relación jerarquizada" (Pageaux). Ya en la segunda mitad de siglo se impone una documentación diferenciada y hasta estadística de la vida cultural en Mendoza, que desemboca en el entorno del 1900 en el estereotipo de un asombroso progreso argentino, registrado también en Mendoza.
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El objetivo del presente trabajo fue comparar la eficiencia de 4 pesticidas: dimetoato, metidation, etion y clorpirifos, en el control de la cochinilla H [Saissetia oleae Bernard (Homoptera, Coccoidea, Lecaniidae)] también llamada cochinilla negra del olivo. Estos productos, conocidos en Mendoza (Argentina), se utilizan localmente. El ensayo se realizó en Vistalba (Luján de Cuyo). Para la evaluación se tuvo en cuenta el porcentaje de mortalidad. El análisis estadístico se efectuó transformando los datos según arcsen ( x / 1 0 0 ) .
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En países en vías de desarrollo como Argentina, la sobrevida de prematuros de peso inferior a 1000 gramos dista mucho de los resultados reportados por países desarrolladas. Controles prenatales deficitarios, recursos técnicos limitados y la saturación de los servicios de Neonatología son en parte responsables de estas diferencias. Una de las situaciones frecuentemente asociada a decisiones éticas en neonatología se produce en torno al prematuro extremo. Las preguntas más difíciles de responder son si existe un límite de peso o edad gestacional por debajo del cual no se deban iniciar o agregar terapéuticas encaminadas a salvar la vida, por considerarlas inútiles para el niño, prolongan sin esperanza la vida, hacen sufrir al paciente y su familia y ocupar una unidad que priva de atención a otro niño con mayores posibilidades de sobrevida. En el presente estudio se elaboró un score de riesgo neonatal constituido por variables que caracterizan a muchas poblaciones de nuestros países latinoamericanos y que fue validado estadísticamente.El score es de rápida y fácil realización. Permite predecir si el prematuro grave es recuperable o no, posibilitando tomar decisiones éticas basadas en una técnica validada, que permite actuar en el mayor beneficio del niño y su familia, al mismo tiempo que se hace un uso más equitativo de los recursos.
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La producción de álamos en la pampa ondulada de la provincia de Buenos Aires podría constituir una actividad alternativa y/o complementaria, debido a zonas ecológicas favorables para su cultivo. En este contexto es importante conocer el comportamiento de los clones en los diversos ambientes para poder definir cuáles de ellos podrían presentar mayor estabilidad para los diferentes sitios. El objetivo del trabajo fue estudiar la interacción existente entre los parámetros de crecimiento y supervivencia de 16 clones de Populus spp. en dos micrositios geomorfológicamente diferentes en la región pampeana, Argentina. Los clones en estudio provienen de cruzamientos intraespecíficos de P. deltoides e interespecíficos de P. deltoides x P. nigra (Populus x canadensis). Se plantaron en dos ensayos, uno por cada situación geomórfica: loma y bajo, y se completó con un análisis estadístico comparando los ensayos en forma individual y conjunta. Cada ensayo se instaló con un diseño de bloques completos al azar. Las variables analizadas fueron la supervivencia, la altura media y el área basal al concluir el segundo año de crecimiento. Para el sitio regional evaluado, la interacción entre los clones y los micrositios fue significativa para las variables altura y supervivencia. La mayor disponibilidad de agua en el micrositio bajo produjo mayores crecimientos clonales con diferencias significativas respecto del micrositio loma. La estabilidad de los atributos de supervivencia y crecimiento frente a los micrositios es un objetivo fundamental en las plantaciones clonales. Siendo los micrositios una realidad ambiental importante, propia como variable no controlable, la reducción de la variabilidad de respuesta ante ellos permitiría la constitución de unidades de manejo más homogéneas.
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En el ámbito de la llanura pampeana tienen lugar procesos degradativos que condicionan la actividad agrícola ganadera, vinculados con la erosión de tipo hídrica superficial. El presente trabajo busca modelar la emisión de sedimentos en una cuenca hidrográfica con forestaciones del Noreste Pampeano. La metodología implementada consiste en aplicar un modelo cartográfico cuantitativo desarrollado en base geoespacial con Sistema de Información Geográfica, apoyado en la Ecuación Universal de Pérdida de Suelo Modificada (MUSLE). Se realizó un análisis de validación estadística con ensayos de microsimulador de lluvias a campo, para una lluvia de 30 mm.h-1 de dos años de retorno. Los resultados obtenidos fueron mapas georreferenciados de cada factor de la MUSLE valorizados por color-intensidad, que alcanzan un valor de 33,77 Mg de sedimentos emitidos a la salida de la cuenca, con un coeficiente de correlación de 0,94 y un grado de ajuste de Nash-Sutcliffe de 0,82. Se concluye que el modelo cartográfico generó información espacial precisa de los componentes de la MUSLE para un evento de lluvia concreto. La aplicación del microsimulador de lluvias permitió la obtención de valores reales de emisión de sedimentos, lográndose un alto grado de ajuste. La emisión de sedimentos en la cuenca resultó ser leve a nula.
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Este es un estudio sobre utilización de medicamentos donde se analiza la evolución de la prescripción, en DAMSU de UNCuyo, de los 14 grupos terapéuticos (GT) de la clasificación ATC, durante 4 años consecutivos. Su objetivo fue determinar la prevalencia de las prescripciones en los 3 primeros niveles de la clasificación. Los datos fueron recolectados en los meses de abril, junio, setiembre y diciembre utilizando la metodología del DURG y procesados con un programa EPI INFO. Las comparaciones estadísticas fueron realizadas mediante la Prueba no paramétrica de los Signos. El ranking de GT fue constante pero el total de prescripciones disminuyó significativamente entre 2004 y 2007. Los GT del 1º nivel: S. Nervioso (N), S. cardiovascular (C), Digestivo y Metabolismo (A) y Músculo-esquelético (M), ocuparon, en orden decreciente, los cuatro primeros puestos del ranking durante los 4 años. De estos GT fueron analizados los subgrupos del 2º y 3º nivel. La prescripción de Psicolépticos + Psicoanalépticos superó a la de Analgésicos en el grupo N. En el grupo C los Agentes Antihipertensivos, y entre ellos los IECAs, encabezaron el ranking. Las vitaminas fueron las primeras en el GT A y el subgrupo de Antiinflamatorios y Antirreumáticos en el GT M. Se discuten estos resultados en función de la racionalidad de las prescripciones.
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Este trabajo muestra los resultados de una encuesta realizada en 2010 sobre consumo de drogas adictivas en alumnos de 7 Facultades de la UNCUYO y los compara con los resultados obtenidos 12 años antes con una encuesta equivalente. La encuesta fue semiestructurada, con 17 preguntas, autocumplimentada, individual y anónima, con una muestra de 1108 alumnos de ambos sexos. De esa encuesta se utilizaron 7 preguntas específicas sobre drogas adictivas y una pregunta sobre consumo de medicamentos en general, con 46 opciones entre las que figuraban 10 denominaciones comerciales de benzodiacepinas, como drogas adictivas de prescripción. Para las comparaciones estadísticas se utilizó Chi cuadrado. El ranking de drogas utilizadas fue relativamente similar en 1998 y 2010 pero, exceptuando tabaco y “otras drogas" que se mantuvieron estables, el resto aumentó alrededor de 4 veces en el periodo. El 82,8% de los alumnos manifestó consumir alcohol (siempre + a veces); de 1 a 5 vasos semanales el 79%. En todas las Facultades, cerveza y Fernet encabezaron el ranquing de preferencias por bebidas alcohólicas. La prevalencia del consumo de tabaco en el total de la muestra se mantuvo constante en 1998 y 2010 (alrededor del 28%) pero el consumo entre Facultades fue variable y en Artes fue significativamente más elevado (42%). Siguen en el ranking marihuana con 10% de prevalencia, tranquilizantes con alrededor del 6% y cocaína con poco más del 1%. Finalmente “otras drogas" (Hachis, LSD, extasis, anabólicos, anfetaminas, “hongos") representaron solamente un 3% de prevalencia. Artes y Ciencias Políticas mostraron las mayores prevalencias de consumo y Derecho e Ingeniería las menores. Esto indica implementar acciones preventivas y correctivas particulares para cada Facultad.
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En este trabajo abordamos el análisis de experiencias exiliares de trabajadores chilenos que se radicaron en el Noreste de la Provincia de Chubut, en Patagonia Argentina, después de producido el golpe de estado contra el presidente democrático Salvador Allende Gossens, en Septiembre de 1973. Cuando revisé la factibilidad de la investigación, y en mérito a los escasos repositorios documentales, decidí, dando continuidad a indagaciones previas, trabajar con historia oral. Esta metodología o práctica, involucra una dimensión personal, subjetiva y afectiva, que supone una constante relación entre los sujetos que participan, lo que implica una cualitativa diferencia en relación a las fuentes más tradicionales. No minimizo el valor de la estadística, pero hago una opción por nombrar y conocer a quienes han compartido con nosotros vivencias y experiencias, explicitando nuestra inscripción en la construcción de la información documental, no objetivándonos. El trabajo desarrollado se halla en la encrucijada entre la historia del pasado reciente y la memoria; con una perspectiva "desde abajo", buscando conjugar la no uniformidad de la experiencia humana, con la pretensión de generalidad y explicación de la ciencia social. Las narraciones o testimonios obtenidos las he revisado, procurando develar las representaciones que subyacen, y comprendiendo el modo en que actuaron. Las memorias tienen un carácter subjetivo y en permanente transformación, lo que en cierto sentido puede singularizarlas, pero como historiadores debemos inscribirlas en un contexto histórico global, para procurar esclarecer las causas, las condiciones, y las estructuras, aportando a una historia total. Hemos rescatado prácticas, percepciones, y discursos; develando la importancia del trabajo como factor organizador y estabilizador, al dotar a estos sujetos, de un sitio en la sociedad receptora, y permitiéndoles "ir desarmando sus valijas", es decir, ir superando la transitoriedad. Al caracterizar al exilio chileno, en el contexto internacional y local; y atendiendo a las escasas producciones que dan cuenta del universo obrero en estas experiencias traumáticas, han sido evidentes los límites que supone una estricta separación entre exilio, y migración económica o política; ya que dicha conceptualización encierra una mirada que invisibiliza derroteros que en principio, o superficialmente, pueden ser leídos como poco organizados. La aplicación del análisis de red, por cierto contribuyó a hacerlos visibles, transformándolos en actores racionales, con objetivos que se movilizaron a partir de los recursos de que dispusieron; tratando de superar el paradigma que hacía de ellos seres desesperados: fueron mujeres y hombres que eligieron un destino posible, siempre atendiendo al doble carácter de la experiencia en que estuvieron inmersos: la salida de su país por un lado los liberó, pero también los privó; asociando indisolublemente sentimientos de dolor por el desprendimiento de lo propio -de los afectos personales y colectivos-, agravados por los efectos de la derrota y la incertidumbre. Son sujetos que pusieron su identidad en riesgo. Pretendemos lograr que esta investigación, no sea sólo un estudio de caso, sino que pueda inscribirse a partir de su especificidad, en tanto exilio obrero, en una perspectiva comparativa, superando una definición espacial específica, en el Nor Este de Chubut.