Pigeot, Iris
Loading...
Preferred name
Pigeot, Iris
Official Name
Pigeot, Iris
2 results
Now showing 1 - 2 of 2
- Some of the metrics are blocked by yourconsent settings
Item type:Publication, Der Conditional Synergy Index --Ein Maß zur Bestimmung einer Gen-Gen-Interaktion basierend auf graphischen Modellen(2008-09-05); ; ; In genetic studies of complex diseases, it is important to identify and qualify gene-gene interactions. Interaction is often defined as deviance from genetic additive effects. But this statistical definition needs not to reflect the genes' biological interactions. I propose a new method to detect gene-gene interaction that exploits the concept of synergy and antagonism, which is said to capture biological relationships. The conditional synergy index (CSI) classifies and quantifies interaction on the penetrance scale. The general theory under two-locus disease models is developed. The index assumes a cohort design and genotypes to be dichotomized into risk-genotypes (exposed) and non-risk-genotypes (unexposed) but it does not assume the loci to be in linkage equilibrium. In simulation studies the performance of the CSI, its estimator and variance is investigated and compared to the performance of various epidemiological interaction measure like e.g. Rothman's syngergy index and to appropriate bootstrap estimators. The results exhibit that in contrast to common interaction measures, only the CSI is adequat to detect interaction on the penetrance scale. However, the proposed estimator of the CSI shows a slow convergence.doctoral thesis278 168 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Geostatistical Modeling of Built Environment Characteristics of Urban Moveability(2015-08-14); ; ; Physical inactivity is considered as a major risk factor for non-communicable diseases. In particular, technological developments and environmental changes led to a decrease of physical activity in daily life. In the last two decades, the investigation of factors influencing physical activity more and more focused on characteristics of the built environment and identified opportunities as well as barriers for physical activity. The walkability concept was established to investigate the association between the built environment and physical activity. This research starts from a walkability index that combines urban measures for residential density, land use mix, and street connectivity. The walkability index was mainly used to investigate neighborhoods that support physical activity with regard to active transport of adults in everyday life. In this thesis, the walkability concept was expanded in order to assess walkability measures and recreational facilities that affect physical activity in European children. A new concept was introduced to capture opportunities for physical activity in the neighborhood of children, called moveability index.doctoral thesis639 322