title: On variation and uncertainty.
authors.affiliation: University Maastricht, Maastricht, the Netherlands. jimmie.leppink@maastrichtuniversity.nl.
authors.forename: Jimmie
authors.initials: J
authors.lastname: Leppink
authors.affiliation: University of California, San Francisco, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: O'Sullivan
authors.affiliation: The Commonwealth Medical College, Pennsylvania, USA.
authors.forename: Kal
authors.initials: K
authors.lastname: Winston