In the framework of regression, consider the set of regression submodels. By submodel, we mean on e or more response variables and a subset of the potential regressors. Imagine the submodels as a ponts in some space. How can we "project" these ponts onto a map so as to visualize and compare...

We examine in this paper various consequences of the Poincari separation theorem. First, Poincari's theorem is used to prove results establishing a constrainted principal component analysis, both at the sample and at the population level. Introduction of constraints in principal component...