Funcionamiento diferencial del ítem y puntuaciones de corte: implicaciones en la interpretación de las puntuaciones de los tests

Psychological and educational measurement instruments are used to make decisions that can have an important impact on the person being assessed. It is therefore essential to ensure that tests are free from bias so that the scores they yield provide a fair interpretation. This study aimed to assess the impact that items showing differential functioning may have on test interpretations based on cut-off scores. To this end a simulation study was conductedin which we manipulated the size of the comparison groups (100, 250,500 and 1000), the magnitude of differential item functioning (DIF) (set at 0.8 for the difference between the difficulty parameters of the two groups) and the degree of test contamination (0%, 10%, 20%, 30% and 40% of items with differentialfunctioning). Overall, the simulation considered 20 conditions, 1000 replications and a 20-item test. Results indicated that the selected cut-off did have an influence, and as the degree of test contamination increased, greater differences between the groups were erroneously detected, both in terms of statistical test significance and effect size obtained. These findings highlight the importance of ensuring that measurement instruments are free from DIF so that the interpretation of scores is both accurate and fair, this being a key aspect of a test’s validity.Los instrumentos de medida psicológicos y educativos se emplean en la toma de decisiones que afectan de modo relevante a las personas evaluadas. Por ello es clave que se garantice una interpretación equitativa de las puntuaciones obtenidas, mediante la utilización de tests no sesgados. El objetivo del trabajo es valorar el impacto de la presencia de ítems con funcionamiento diferencial en las interpretaciones basadas en puntuaciones de corte. Para ello se diseñó un estudio de simulación en que se manipuló el tamaño muestral de los grupos de comparación (100, 250, 500 y 1000), la magnitud de funcionamiento diferencial del ítem (establecida en 0.8 como diferencias entre los parámetros de dificultad de ambos grupos) y el grado de contaminación del test (0%, 10%, 20%, 30% y 40% de ítems con funcionamiento diferencial). En total se trabajó con 20 condiciones, 1000 réplicas y un test  de 20 ítems. Los resultados evidenciaron la influencia del punto de corte seleccionado y mostraron que a mayor grado de contaminación del test se detectan erróneamente mayores diferencias entre los grupos de comparación, tanto a nivel de la prueba de significación como del tamaño del efecto estudiados. Todo ello permite concluir la relevancia de obtener evidencias de ausencia de DIF en los instrumentos de medida para lograr una interpretación precisa y equitativa de sus puntuaciones, en el marco de la validez del test

Differential item functioning and cut-off scores: Implications for test score interpretation

Psychological and educational measurement instruments are used to make decisions that can have an important impact on the person being assessed. It is therefore essential to ensure that tests are free from bias so that the scores they yield provide a fair interpretation. This study aimed to assess the impact that items showing differential functioning may have on test interpretations based on cut-off scores. To this end a simulation study was conductedin which we manipulated the size of the comparison groups (100, 250,500 and 1000), the magnitude of differential item functioning (DIF) (set at 0.8 for the difference between the difficulty parameters of the two groups) and the degree of test contamination (0%, 10%, 20%, 30% and 40% of items with differentialfunctioning). Overall, the simulation considered 20 conditions, 1000 replications and a 20-item test. Results indicated that the selected cut-off did have an influence, and as the degree of test contamination increased, greater differences between the groups were erroneously detected, both in terms of statistical test significance and effect size obtained. These findings highlight the importance of ensuring that measurement instruments are free from DIF so that the interpretation of scores is both accurate and fair, this being a key aspect of a test's validity

Implementation of at-line capillary zone electrophoresis for fast and reliable determination of adenovirus concentrations in vaccine manufacturing

A CZE method was validated and implemented for fast and accurate in-process determination of adenovirus concentrations of downstream process samples obtained during manufacturing of adenovirus vector-based vaccines. An analytical-quality-by-design approach was embraced for method development, method implementation, and method maintenance. CZE provided separation of adenovirus particles from sample matrix components, such as cell debris, residual DNA and proteins. The intermediate precision of the virus particle concentration was 6.9% RSD and the relative bias was 2.3%. In comparison, the CZE method is intended to replace a quantitative polymerase chain reaction method which requires three replicates in three analytical runs to achieve an intermediate precision of 8.1% RSD. Given that, in addition, the time from sampling till reporting results of the CZE method was less than 2 h, whereas quantitative polymerase chain reaction requires 3 days, it follows that the CZE method enables faster processing times in downstream processing

Francisca Galindo-Garre - Testing Models with Inequality Constraints in Contingency Tables Using Posterior Predictive Check Distributions

Content: An empirical example; An order-constrained log-linear model; Classical p values; Plug-in p values; Posterior predictive p values; Discussio

Differential item functioning and cut-off scores: Implications for test score interpretation

Los instrumentos de medida psicológicos y educativos se emplean en la toma de decisiones que afectan de modo relevante a las personas evaluadas. Por ello es clave que se garantice una interpretación equitativa de las puntuaciones obtenidas, mediante la utilización de tests no sesgados. El objetivo del trabajo es valorar el impacto de la presencia de ítems con funcionamiento diferencial en las interpretaciones basadas en puntuaciones de corte. Para ello se diseñó un estudio de simulación en que se manipuló el tamaño muestral de los grupos de comparación (100, 250, 500 y 1000), la magnitud de funcionamiento diferencial del ítem (establecida en 0.8 como diferencias entre los parámetros de dificultad de ambos grupos) y el grado de contaminación del test (0%, 10%, 20%, 30% y 40% de ítems con funcionamiento diferencial). En total se trabajó con 20 condiciones, 1000 réplicas y un test de 20 ítems. Los resultados evidenciaron la influencia del punto de corte seleccionado y mostraron que a mayor grado de contaminación del test se detectan erróneamente mayores diferencias entre los grupos de comparación, tanto a nivel de la prueba de significación como del tamaño del efecto estudiados. Todo ello permite concluir la relevancia de obtener evidencias de ausencia de DIF en los instrumentos de medida para lograr una interpretación precisa y equitativa de sus puntuaciones, en el marco de la validez del test.Psychological and educational measurement instruments are used to make decisions that can have an important impact on the person being assessed. It is therefore essential to ensure that tests are free from bias so that the scores they yield provide a fair interpretation. This study aimed to assess the impact that items showing differential functioning may have on test interpretations based on cut-off scores. To this end a simulation study was conductedin which we manipulated the size of the comparison groups (100, 250,500 and 1000), the magnitude of differential item functioning (DIF) (set at 0.8 for the difference between the difficulty parameters of the two groups) and the degree of test contamination (0%, 10%, 20%, 30% and 40% of items with differentialfunctioning). Overall, the simulation considered 20 conditions, 1000 replications and a 20-item test. Results indicated that the selected cut-off did have an influence, and as the degree of test contamination increased, greater differences between the groups were erroneously detected, both in terms of statistical test significance and effect size obtained. These findings highlight the importance of ensuring that measurement instruments are free from DIF so that the interpretation of scores is both accurate and fair, this being a ky aspect of a test’s validity

Dos enfoques analíticos del diseño con grupo control no equivalente para variables dependientes categóricas

El análisis estadístico del diseño con grupo control no equivalente (GCNE) con variables dependientes numéricas ha sido un tema de gran interés durante la última década. Mucho menos interés ha demandado el análisis estadístico con variables dependientes categóricas, aunque las mismas ideas se aplican en ambos casos. No obstante, los problemas generados por el error de medida de pretest (y postest) y las variables omitidas dificultan en mayor medida un análisis correcto. En este trabajo se aborda un análisis comparativo de dos enfoques recientemente propuestos para el análisis estadístico del diseño GCNE: el modelo lineal de crédito parcial (Fischer y Ponocny, 1994, 1995) y el modelo multivariante categórico de medidas repetidas (Agresti, 1996, 1997). La interpretación de los resultados con ambos enfoques se apoya en un ejemplo del campo clínico