Assessing the Precision of Compositional Data in a Stratified Double Stage Cluster Sample: Application to the Swiss Earnings Structure Survey

Precision of released figures is not only an important quality feature of official statistics, it is also essential for a good understanding of the data. In this paper we show a case study of how precision could be conveyed if the multivariate nature of data has to be taken into account. In the official release of the Swiss earnings structure survey, the total salary is broken down into several wage components. We follow Aitchison's approach for the analysis of compositional data, which is based on logratios of components. We first present diferent multivariate analyses of the compositional data whereby the wage components are broken down by economic activity classes. Then we propose a number of ways to assess precision

Percepción de las consecuencias del consumo de tabaco en fumadores adictos al juego

En una muestra de 34 adictos al juego en tratamiento, se examinan las características de consumo de tabaco de los sujetos fumadores y la influencia de las consecuencias percibidas de la conducta de fumar en función de las etapas de cambio (Prochaska, DiClemente y Norcross, 1992). Los resultados muestran que, aunque los porcentajes de fumadores doblan a los existentes en la población general, las personas fumadoras adictas al juego están representadas en las diferentes etapas de cambio con porcentajes parecidos a los de dicha población. Por otra parte, no se ha encontrado relación entre el nivel de dependencia medido con el Test de Fagerström y la etapa de cambio. En cuanto a la influencia de las consecuencias percibidas del consumo de tabaco, en general los sujetos tienden a conceder mayor importancia a los perjuicios que a los beneficios de fumar. En los análisis en función de las etapas de cambio, se encuentran diferencias significativas entre el grupo de los que piensan dejar de fumar en los próximos seis meses, (contempladores y preparados) y el grupo de los que no fuman (exfumadores y no fumadores) en el beneficio “fumar ayuda a relajarse” que es más valorado por los primeros. También se encuentran dichas diferencias entre los precontempladores y los que no fuman en dos perjuicios: “fumar produce a veces dolor de cabeza” y “fumar a veces provoca taquicardia” que son más valorados por los segundos. Estos resultados sugieren la conveniencia de realizar las intervenciones más adecuadas para cada etapa de cambio, a fin de que las personas adictas al juego puedan también tener éxito en el abandono de la adicción al tabaco

Estimation of age- and stage-specific Catalan breast cancer survival functions using US and Catalan survival data

During the last part of the 1990s the chance of surviving breast cancer increased. Changes in survival functions reflect a mixture of effects. Both, the introduction of adjuvant treatments and early screening with mammography played a role in the decline in mortality. Evaluating the contribution of these interventions using mathematical models requires survival functions before and after their introduction. Furthermore, required survival functions may be different by age groups and are related to disease stage at diagnosis. Sometimes detailed information is not available, as was the case for the region of Catalonia (Spain). Then one may derive the functions using information from other geographical areas. This work presents the methodology used to estimate age- and stage-specific Catalan breast cancer survival functions from scarce Catalan survival data by adapting the age- and stage-specific US functions. Methods: Cubic splines were used to smooth data and obtain continuous hazard rate functions. After, we fitted a Poisson model to derive hazard ratios. The model included time as a covariate. Then the hazard ratios were applied to US survival functions detailed by age and stage to obtain Catalan estimations. Results: We started estimating the hazard ratios for Catalonia versus the USA before and after the introduction of screening. The hazard ratios were then multiplied by the age- and stage-specific breast cancer hazard rates from the USA to obtain the Catalan hazard rates. We also compared breast cancer survival in Catalonia and the USA in two time periods, before cancer control interventions (USA 1975–79, Catalonia 1980–89) and after (USA and Catalonia 1990–2001). Survival in Catalonia in the 1980–89 period was worse than in the USA during 1975–79, but the differences disappeared in 1990–2001. Conclusion: Our results suggest that access to better treatments and quality of care contributed to large improvements in survival in Catalonia. On the other hand, we obtained detailed breast cancer survival functions that will be used for modeling the effect of screening and adjuvant treatments in Catalonia