Sytze de Bruin Arnold Bregt Marc van de Ven Assessing fitness for use: the expected value of spatial data sets. 457-471 2001 15 International Journal of Geographical Information Science 5 http://taylorandfrancis.metapress.com/openurl.asp?genre=article&issn=1365-8816&volume=15&issue=5&spage=457 db/journals/gis/gis15.html#BruinBV01