Robustness Analysis (RA) is a problem structuring method for flexible plann
ing. This paper presents a revised definition of RA which is based on earli
er presentations of RA as well as new results derived from empirical resear
ch. This gaper first identifies the basic concepts that are necessary for a
rigorous definition of RA and relationships between these concepts. On thi
s foundation, this paper constructs new definitions of robustness score and
discusses their uses.