  To provide users insight into the value and limits of world university
rankings, a comparative analysis is conducted of 5 ranking systems: ARWU,
Leiden, THE, QS and U-Multirank. It links these systems with one another at the
level of individual institutions, and analyses the overlap in institutional
coverage, geographical coverage, how indicators are calculated from raw data,
the skewness of indicator distributions, and statistical correlations between
indicators. Four secondary analyses are presented investigating national
academic systems and selected pairs of indicators. It is argued that current
systems are still one-dimensional in the sense that they provide finalized,
seemingly unrelated indicator values rather than offering a data set and tools
to observe patterns in multi-faceted data. By systematically comparing
different systems, more insight is provided into how their institutional
coverage, rating methods, the selection of indicators and their normalizations
influence the ranking positions of given institutions.
