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Introducción: La determinación de la calidad de un instrumento de medición implica la evaluación tanto de la exactitud como de la estabilidad de dicha medición o el resultado. Objetivo: Evaluar el índice de dificultad y discriminación de los ítems de los instrumentos de medición de algunas asignaturas del eje curricular de Fundamentos de la medicina de una escuela de medicina particular. Métodos: Mediante estudio observacional, comparativo, transversal y prolectivo, se analizaron los ítems del examen ordinario de las asignaturas Morfología, Bioquímica y Biología Molecular, y Microbiología y Virología Médica, los cuales fueron contestados por 112 alumnos de Morfología, 101 de Bioquímica y Biología Molecular y 89 de Microbiología y Virología Médica. El número de reactivos resultó 100 para Morfología, 80 para Bioquímica y Biología Molecular y 75 para Microbiología y Virología Médica. Se utilizó estadística descriptiva, y se calculó el índice de dificultad y el índice de discriminación de los ítems y de todo el examen. Además, se utilizó ANOVA, considerando estadísticamente significativo un resultado igual o menor a 0,05. Resultados: Los ítems resultaron más difíciles en el examen de Morfología, ya que el 19 por ciento correspondió a la clasificación de relativamente difíciles y el 50 por ciento a la de difíciles, con un total del 69 por ciento entre relativamente difíciles y difíciles. El índice de discriminación resultó mayor en la asignatura de Microbiología y Virología Médica, mientras que en Bioquímica y Biología Molecular se presentó una buena capacidad de discriminación. Conclusiones: Existió variabilidad en el grado de dificultad y el poder de discriminación de los ítems de los exámenes analizados(AU)

Introduction: Determining the quality of a measuring instrument implies the evaluation of both the accuracy and the stability of such measurement or result. Objective: To evaluate the index of difficulty and discrimination of the items of the measuring instruments of some subjects of the curricular axis of Fundamentals of Medicine of a particular medical school. Methods: By means of an observational, comparative, cross-sectional and prolective study, the items of the ordinary examination of the subjects Morphology, Biochemistry and Molecular Biology, and Microbiology and Medical Virology were analyzed, which were answered by 112 students of Morphology, 101 of Biochemistry and Biology Molecular, and 89 of Microbiology and Medical Virology. The number of reagents was 100 for Morphology, 80 for Biochemistry and Molecular Biology, and 75 for Microbiology and Medical Virology. Descriptive statistics were used, and the difficulty index and the discrimination index of the items and of the entire exam were calculated. In addition, ANOVA was used, considering a statistically significant result equal to or less than 0.05. Results: The items were more difficult in the Morphology test, since 19 percent corresponded to the classification of relatively difficulty and 50 percent corresponded to those of difficulty, with a total of 69 percent between relative difficulty and difficulty. The discrimination index was higher in the subject of Microbiology and Medical Virology, while in Biochemistry and Molecular Biology there was a good capacity for discrimination. Conclusions: There was variability in the degree of difficulty and the power of discrimination of the items of the analyzed exams(AU)

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The Neotropical otter, Lontra longicaudis, is an ecologically important species for freshwater ecosystems that is threatened due to habitat destruction and hunting. However, there is limited information regarding the population sizes, genetic diversity, genetic structure and gene flow of the species, which is crucial for the elaboration of conservation plans. The aim of this study was to isolate and characterize microsatellites for L. longicaudis, using Illumina paired-end-sequencing. Initial amplification tests were performed in 48 loci, out of which, 13 yielded high-quality PCR products and thus were further evaluated. Genetic diversity and discrimination power of the 13 microsatellite loci was assessed using 19 non-invasive samples collected in the Jamapa basin in Veracruz, Mexico and blood samples from six captive individuals. All loci were polymorphic, the number of alleles per locus ranged from 4 to 10, the observed heterozygosity from 0.21 to 0.69, and the expected heterozygosity from 0.55 to 0.82. The combined set of 13 microsatellites showed a high power for discriminating among individuals (probability of identity PID = 1.551 × 10-16) and among siblings (probability of identity of siblings PIDSIB = 3.349 × 10-06). A combination of nine loci are sufficient to discriminate among siblings with high confidence (PIDSIB < 0.0001). The new set of microsatellites for the Neotropical otter reported here will provide a useful genetic tool to assess population genetic patterns and ecological parameters of the species.

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Background: The present study was undertaken towards the development of SSR markers and assessing genetic relationships among 32 date palm (Phoenix dactylifera L.) representing common cultivars grown in different geographical regions in Saudi Arabia. Results: Ninety-three novel simple sequence repeat markers were developed and screened for their ability to detect polymorphism in date palm. Around 71% of genomic SSRs were dinucleotide, 25% tri, 3% tetra and 1% penta nucleotide motives. Twenty-two primers generated a total of 91 alleles with a mean of 4.14 alleles per locus and 100% polymorphism percentage. A 0.595 average polymorphic information content and 0.662 primer discrimination power values were recorded. The expected and observed heterozygosities were 0.676 and 0.763 respectively. Pair-wise similarity values ranged from 0.06 to 0.89 and the overall cultivars averaged 0.41. The UPGMA cluster analysis recovered by principal coordinate analysis illustrated that cultivars tend to group according to their class of maturity, region of cultivation, and fruit color. Analysis of molecular variations (AMOVA) revealed that genetic variation among and within cultivars were 27% and 73%, respectively according to geographical distribution of cultivars. Conclusions: The developed microsatellite markers are additional values to date palm characterization tools that can be used by researchers in population genetics, cultivar identification as well as genetic resource exploration and management. The tested cultivars exhibited a significant amount of genetic diversity and could be suitable for successful breeding program. Genomic sequences generated from this study are available at the National Center for Biotechnology Information (NCBI), Sequence Read Archive (Accession numbers. LIBGSS_039019).

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Se realizó un estudio descriptivo y transversal combinado con enfoques cualitativos, a fin de evaluar la calidad de los exámenes de control parcial aplicados a 30 médicos de primero y segundo años residentes en medicina general integral, que laboraban en el Hospital Clinicoquirúrgico Docente "Dr. Joaquín Castillo Duany" de Santiago de Cuba, durante el año 2014. Se emplearon métodos teóricos, empíricos y de procesamiento estadístico en el análisis de los instrumentos de evaluación. Ambos exámenes teóricos presentaron diferencias y similitudes constatadas a través de indicadores, tales como número de horas asignadas al contenido y cantidad de incisos empleados en la exploración, índice de dificultad por temáticas y preguntas, así como nivel de discriminación y consistencia interna del instrumento, todo lo cual ofreció validez y confiabilidad para el sistema de evaluación del aprendizaje.

A descriptive and cross-sectional study with qualitative approaches was carried out, in order to evaluate the quality of the exams of partial control applied to 30 doctors of first and second years of residency in Comprehensive General Medicine, who worked in "Dr. Joaquín Castillo Duany" Teaching Clinical Surgical Hospital from Santiago de Cuba, during the year 2014. Theoretical, empiric methods were used as well as those of statistical processing in the analysis of the evaluation tools. Both theoretical exams presented differences and similarities verified through indicators, such as number of hours assigned to the content and quantity of subsections used in the exploration, index of difficulty by theme and question, as well as discrimination level and internal consistency of the tool, all of which offered validity and reliability for the evaluation system of learning.

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Introducción: el índice de dificultad y el poder de discriminación son indicadores fáciles de calcular y útiles para el análisis de la correspondencia entre los resultados esperados y los obtenidos de un instrumento evaluativo. Objetivo: evaluar la calidad de las preguntas del examen final ordinario de Morfofisiología Humana V. Métodos: fueron incluidos en esta investigación los 265 exámenes teóricos realizados por los estudiantes del segundo año en la Facultad de Medicina No. 2 de la Universidad de Ciencias Médicas de Santiago de Cuba, durante el curso 2011-2012, a los que se les calculó el índice de dificultad y el poder de discriminación en cada una de las 7 preguntas aplicadas. Resultados: las preguntas de respuesta alternativa, que evaluaban los contenidos sobre la sangre y el corazón, mostraron un índice de dificultad por debajo de 0,1 y un poder de discriminación inferior a 0,2, lo que hace necesaria su reformulación en próximos instrumentos evaluativos. Los valores más altos para ambos indicadores fueron 0,34 y 0,86, respectivamente, y correspondieron a una pregunta de selección múltiple sobre vasos sanguíneos y linfáticos, siguiéndoles en orden las preguntas de respuesta abierta. Conclusiones: se demostró la pertinencia de la mayoría de las preguntas, destacándose la capacidad de 5 de ellas para distinguir estudiantes de alto y bajo rendimientos.

Introduction: the difficulty index and the discrimination power are easy indicators to calculate and useful for the analysis of the correspondence between the expected and obtained results of an evaluative instrument. Objective: to evaluate the quality of questions of the regular final examination of Human Mophophysiology V. Methods: the 265 theoretical examinations carried out by the second year students in the Medical Faculty No. 2 of the Medical University in Santiago de Cuba, during the course 2011-2012 were included in this investigation, to which the difficulty index and the discriminating power were calculated in each of the 7 applied questions. Results: the questions with alternative answer which evaluated the contents on blood and heart, showed a difficulty index below 0.1 and a discriminating power lower than 0.2, making necessary their reformulation in future evaluative instruments. The highest values for both indicators were 0.34 and 0.86, respectively, and they corresponded to a question of multiple selections on blood and lymphatic vessels, followed in order by the questions of open answer. Conclusions: the relevancy of most of the questions was demonstrated, and the capacity of 5 of them to distinguish students of high and low performances was emphasized.

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O estudo investiga o impacto da introdução de uma nova classe de erros no subteste de leitura do Teste de Desempenho Escolar na distribuição dos escores. Participaram do estudo 306 crianças de 1ª a 4ª séries da rede de ensino de Belo Horizonte. Para cada participante foram conferidos dois escores: um estabelecido a partir de critério do manual (EB1) e o outro a partir do critério adotado no presente estudo (EB2) - que considerou incorretas as respostas de silabação e de correção espontânea. Os resultados mostraram que a adoção do critério EB2 tornou o teste mais discriminativo, mas não impediu o aparecimento de um efeito de teto, nem proporcionou uma distribuição normal dos escores. As análises mostraram que, além do critério permissivo, o excesso de palavras fáceis e a escassez de palavras difíceis prejudicaram a variabilidade dos escores. Hipóteses sobre a dificuldade das palavras são discutidas à luz da psicolinguística.

The study investigates the impact of the introduction of a new class of errors within the original error set of the reading subtest of the Performance School Test on the distribution of the scores. The sample consisted of 306 1st - 4th grades of the school system of Belo Horizonte who participated in the study. For each child two scores were given: one based on the manual criteria (EB1) and the other on the criteria introduced in the present study (EB2) - which considered explicit sounding out of syllables or of part of the stimuli and self-corrections as incorrect responses. The results showed that the choice of the EB2 made the test more discriminative, but such a modification did not prevent the emergence of a ceiling effect, nor did it enable a normal distribution of the scores. The analysis showed that apart from the permissive criteria the excess of easy words and the shortage of difficult words affected the variability of the scores. Hypotheses about the difficulty of words were discussed in light of the psycholinguistics.

El estudio investiga el influjo que la introducción de una nueva clase de errores en la subprueba de lectura de la Prueba de Rendimiento Escolar tuvo en la distribución de los puntajes de la referida subprueba. Participaron de la investigación 306 niños de 1ª a 4ª clase de la Red de Enseñanza de Belo Horizonte. Para cada participante han sido conferidos dos puntajes: uno establecido a partir de criterio del manual (EB1) y otro a partir del criterio adoptado en la presente investigación (EB2) - que consideró incorrectas las respuestas de silabación y de corrección espontánea. Los resultados han mostrado que la adopción del criterio EB2 tornó la prueba más discriminadora, pero esa modificación no impidió el asomo de un efecto de techo, ni proporcionó una distribución normal de los puntajes. Los análisis han mostrado que, además del criterio permisivo, el exceso de palabras fáciles y la escasez de palabras difíciles perjudicaron la variabilidad de los puntajes. Hipótesis sobre la dificultad de las palabras son discutidas a la luz de la psicolingüística.

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O estudo investiga o impacto da introdução de uma nova classe de erros no subteste de leitura do Teste de Desempenho Escolar na distribuição dos escores. Participaram do estudo 306 crianças de 1ª a 4ª séries da rede de ensino de Belo Horizonte. Para cada participante foram conferidos dois escores: um estabelecido a partir de critério do manual (EB1) e o outro a partir do critério adotado no presente estudo (EB2) - que considerou incorretas as respostas de silabação e de correção espontânea. Os resultados mostraram que a adoção do critério EB2 tornou o teste mais discriminativo, mas não impediu o aparecimento de um efeito de teto, nem proporcionou uma distribuição normal dos escores. As análises mostraram que, além do critério permissivo, o excesso de palavras fáceis e a escassez de palavras difíceis prejudicaram a variabilidade dos escores. Hipóteses sobre a dificuldade das palavras são discutidas à luz da psicolinguística.(AU)

The study investigates the impact of the introduction of a new class of errors within the original error set of the reading subtest of the Performance School Test on the distribution of the scores. The sample consisted of 306 1st - 4th grades of the school system of Belo Horizonte who participated in the study. For each child two scores were given: one based on the manual criteria (EB1) and the other on the criteria introduced in the present study (EB2) - which considered explicit sounding out of syllables or of part of the stimuli and self-corrections as incorrect responses. The results showed that the choice of the EB2 made the test more discriminative, but such a modification did not prevent the emergence of a ceiling effect, nor did it enable a normal distribution of the scores. The analysis showed that apart from the permissive criteria the excess of easy words and the shortage of difficult words affected the variability of the scores. Hypotheses about the difficulty of words were discussed in light of the psycholinguistics.(AU)

El estudio investiga el influjo que la introducción de una nueva clase de errores en la subprueba de lectura de la Prueba de Rendimiento Escolar tuvo en la distribución de los puntajes de la referida subprueba. Participaron de la investigación 306 niños de 1ª a 4ª clase de la Red de Enseñanza de Belo Horizonte. Para cada participante han sido conferidos dos puntajes: uno establecido a partir de criterio del manual (EB1) y otro a partir del criterio adoptado en la presente investigación (EB2) - que consideró incorrectas las respuestas de silabación y de corrección espontánea. Los resultados han mostrado que la adopción del criterio EB2 tornó la prueba más discriminadora, pero esa modificación no impidió el asomo de un efecto de techo, ni proporcionó una distribución normal de los puntajes. Los análisis han mostrado que, además del criterio permisivo, el exceso de palabras fáciles y la escasez de palabras difíciles perjudicaron la variabilidad de los puntajes. Hipótesis sobre la dificultad de las palabras son discutidas a la luz de la psicolingüística.(AU)

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