Some warnings
What lessons can one draw from our short course on ranking, lessons to be formulated as warnings.

Firstly, don't take rankings for granted. Subject them to secondary analysis, using multivariate techniques to check whether they measure what their producers pretend to measure and to check for the dimensions of the measurement (data matrix). Check for the sensitivity of indicators and weights. Beware of manipulation.

Secondly, don't take rankings too seriously. Don't waste time, energy and money on either embracing favorable rankings or on fighting unfavorable ones. Different degrees of fitness for cities, regions, universities and so on do exist. Identify yours and settle for it.

Finally, don't use rankings for benchmarking purposes. Don't waste your money wanting to play in the Champions League, competing with the top players. According to Bain & Company, over the past years benchmarking has become the most popular management technique replacing strategic planning. One should rather search for strategic visions and strategic projects (as in mixed scanning) instead of playing with rankings and benchmarking.

Ranking, instead of being a useful tool, may just be another example of the so-called bikini theory of statistics: it attracts attention, but hides the essential.