<p>I do not know if this is the case at Columbia, but at many universities the tuition and living stipends are provided by outside grant money. As a grad student at Cornell I was supported by a National Health Service fellowship which paid my tuition and a monthly cash stipend of $200/month, big bucks for a grad student in 1975!!! I think NHS functions were rolled into the CDC's National Center for Environmental Health.</p>
<p>However, a warning. Usually these outside fellowship, traineeships. etc are available for a finite time or associated with a particular research project. Mine lasted for only 2 years. For the first 3-1/2 years I was supported by the university-tuition + a monthly stipend of $???. The amount has slipped my mind.</p>
<p>At most research universities, most science/engineering grad students, particularly those in a PhD programs, are well subsitized. That is where much of that grant money goes. There is much less grant money available in the arts, humanities and social sciences. Therefore less of their students are probably subsidized.</p>