In applied research as well as in clinical practice, it is common to evaluate the change that patients experience as a consequence of the treatment they receive. Various methods designed to evaluate this change are reviewed in this study. This review has focused on a specific aspect that has not been given proper attention: the false positive rate. For this reason, a nonchange situation was simulated (pre-post design with no differences between pre and post) and the behavior of 8 different methods was evaluated in this scenario. Different distributions as well as different sample sizes were simulated. A thousand samples were created for each simulated condition. The percentage of times each method detected a change was obtained in order to evaluate the behavior of the selected methods. Because the simulated situation is a nonchange one, any change alert was considered as a false positive. Out of the 8 evaluated methods, the standardized individual difference and the confidence intervals of linear regression are the ones with the best performance. The remaining methods fail to correctly identify and reject sampling random fluctuations. In most cases there is a tendency to consider changes that respond only to random variations as statistically reliable. However, a simple modification related in reliability estimation allows a considerable improvement in the behavior of some methods.

Las minorías migrantes afrontan el estrés aculturativo con respuestas conductuales y cognitivas. Las fuentes de estrés de aculturación incluyen la discriminación, las diferencias socioculturales, la añoranza del origen y la ruptura familiar. Se entrevistaron a 853 inmigrantes peruanos y colombianos en Chile (51% mujeres, y edad M = 33.19; DE = 9.54). Se aplicaron escalas de estrés de aculturación y formas de afrontamiento. La distancia y añoranza familiar fue la principal fuente de estrés siendo mayor entre los colombianos, quienes usan más la movilidad individual, la distracción y las comparaciones sociales, mientras los peruanos internalizan más el estigma del inmigrante. Las comparaciones intergrupales y temporales se relacionaron con menor estrés de aculturación. Se discute la importancia de las formas de afrontar el estrés en minorías migrantes.

The aim of the study is to analyze the mediating effect of self-esteem on the relationship between perceived discrimination and psychological well-being in South American immigrants in Chile. An analytical, cross sectional, non-experimental design was used. We evaluated 853 Peruvians and Colombians living in the northern cities of Arica, Antofagasta, and Santiago de Chile, the capital located in the center of the country. The instruments used were the Ryff Psychological Well-being Scale, the Rosenberg Self-Esteem Scale and the Perceived Discrimination Scale by Basabe, Paez, Aierdi and Jiménez-Aristizabal. We used the estimation method (RWLS) and polychoric correlation matrices, to estimate the effect size and overall fit of the direct effect models of discrimination and self-esteem on psychological well-being, and indirect and total effects of discrimination mediated by self-esteem. While both populations reported similar levels of perceived discrimination, it was found that the means in psychological well-being and self-esteem of the Colombian population were significantly higher than that of the Peruvian population. Regarding self-esteem, the results provided evidence for the possible mediating effect on the relationship between perceived discrimination and psychological well-being. This research aims to contribute to the development of interventions seeking to strengthen self-esteem in order to circumvent possible negative consequences of perceived discrimination, as a consequent, improving immigrants´ personal resources to successfully cope with the diverse demands of their new context.

Resumen: Tanto en la investigación aplicada como en la práctica clínica es habitual tener que evaluar el cambio que experimentan los pacientes como consecuencia del tratamiento que reciben. En este trabajo se valora el comportamiento de varios métodos estadísticos diseñados para estimar ese cambio. La valoración se ha centrado en un aspecto al que todavía no se le ha prestado atención: la tasa de falsos positivos. Para ello, se ha simulado una situación de no-cambio (diseño pre-post sin cambio entre el pre y el post) y se ha valorado el comportamiento de nueve estadísticos distintos en ese escenario. Se han utilizado tres tamaños muestrales distintos (25, 50 y 100) y se han simulado 1000 muestras de cada tamaño. Para evaluar el comportamiento de los estadísticos elegidos se ha calculado el porcentaje de veces que cada estadístico ha detectado un cambio. Puesto que la situación simulada es de no-cambio, cualquier alerta de cambio debe ser considerada un falso positivo. Los resultados obtenidos son bastante llamativos: ninguno de los nueve estadísticos evaluados ofrece un comportamiento aceptable. Únicamente se consiguen resultados aceptables cuando se trabaja con la desviación típica de las diferencias pre-post y se aplican criterios clá-sicos en lugar de los propuestos por la literatura relacionada con la significación clínica. Palabras clave: Cambio clínicamente significativo; diferencia mínimamen-te importante; falsos positivos.Title: Clinical significance: false positives in the estimation of individual change. Abstract: In applied research and in clinical practice we often need to assess the change experienced by patients as a result of the treatment they have received. This paper assesses the performance of several statistical methods designed to estimate such change. This study focuses on one aspect that still has not received attention: the rate of false positives. We have simulated a situation of no-change (pre-post design with no change between pre and post) in which the behavior of nine different statistics have been evaluated. Three different sample sizes (25, 50 and 100) were used and 1000 samples of each size were simulated. To evaluate the behavior of the chosen statistics we have calculated the percentage of times that each statistic has detected change. Since no-change is the simulated situation, any occurrence of change should be considered a false positive. Results are quite striking: none of the nine statistics evaluated offers an acceptable behavior. Good performance is achieved only when the standard deviation of pre-post differences and the traditional criteria are used and not when those proposed by the literature related to the clinical significance are used. Key words: Clinically significant change; minimally important difference; false positives. IntroducciónTanto en la investigación aplicada como en la práctica clínica es habitual tener que evaluar el cambio que experimentan los pacientes como consecuencia del tratamiento que reciben. La cuantificación de ese cambio posee una importanc...

El efecto de la discriminación racial y étnica sobre la autoestima individual y colectiva según el fenotipo autoreportado en migrantes colombianos en Chile The effect of racial and ethnic discrimination on individual and collective self-esteem according to the self-reported phenotype in Colombian migrants in Chile