Gilbert Kollenbach Universtiy of Hagen & University of Siegen   FernUniversität in Hagen Gilbert Kollenbach Hagen, 58084 Germany   gilbert.kollenbach@fernuni-hagen.de   http://www.fernuni-hagen.de/eichner/team/gilbert.kollenbach.shtml           JEL Areas: D1 : Household Behavior: General I : Health, Education, and Welfare