Finer and finer rankings prove anything you want

If you take a single metric from a single ranking and do a bit of slicing by country, region, subject, field and/or age there is a good chance that you can prove almost anything, for example that the University of the Philippines is a world beater for medical research. Here is another example from the Financial Times.

An article by John O'Hagan, Emeritus Professor at Trinity College Dublin, claims that German universities are doing well for research impact in the QS economics world rankings. Supposedly, "no German university appears in the top 50 economics departments in the world using the overall QS rankings. However, when just research impact is used, the picture changes dramatically, with three German universities, Bonn, Mannheim and Munich, in the top 50, all above Cambridge and Oxford on this ranking."

This is a response to Frederick Studemann's claim that German universities are about to move up the rankings. O'Hagan is saying that is already happening.

I am not sure what this is about. I had a look at the most recent QS economics rankings and found that in fact Mannheim is in the top fifty overall for that subject. The QS subject rankings do not have a research impact indicator. They have academic reputation, citations per paper, and h-index, which might be considered proxies for research impact, but for none of these are the three universities in the top fifty. Two of the three universities are in the top fifty for academic research reputation, one for citations per paper and two for h-index.

So it seems that the article isn't referring to the QS economics subject ranking. Maybe it is the overall ranking that professor O'Hagan is thinking of? There are no German universities in the overall top fifty there but there are also none in the citations per faculty indicator. 

I will assume that the article is based on an actual ranking somewhere, maybe an earlier edition of the QS subject rankings or the THE world rankings or from one of the many spin-offs. 

But it seems a stretch to talk about German universities moving up the rankings just because they did well in one metric in one of the 40 plus international rankings in one year.