Indicators in the framework of Partial Order

Indicators play an increasing role in characterizing complex systems and – to some degree – in decision problems, when a ranking is thought of as an intermediate step for a selection of optimal – or depending on external constraints – suboptimal options. When ranking is the aim, we cannot usually describe it by a single indicator. We need a set of indicators, called a Multi-Indicator system (MIS). Typically, an analysis of MIS is confronted with the following problems: • Scaling level: What to do, if the indicators are on a nominal, ordinal, or metric level • Relevance of indicators: Are we confronted with somewhat which may be called information noise? • Role of the inherent characteristic of partial orders, the incomparability. Is incomparability an unavoidable disadvantage? Methods to check these points are presented and critically discussed.