MULTIVARIATE REGRESSION WITH A SINGULAR COVARIANCE MATRIX Dietrich von Rosen Matematisk Statistik, Uppsala Universitet Classical multivariate linear models analysis is extended in order to cover high-dimensional data. The basic assumption is that the dispersion matrix is singular. Consequences of this assumption are studied. Among others the Growth Curve model with a singular dispersion matrix is treated. Both tests and estimators are given. We will show how one can analyse data. Several new aspects appear. For example, sometimes we have to preprocess the data by performing certain projections before using the data in the models.