Rankings are only indicative of certain things but may not reflect the actual situation. SciencesPo, for example, is 4th in Political Sciences rankings but nowhere near that in dev studies rankings. Universities like Wageningen, on the other hand, are in top 20 in dev studies, although SciencesPo and IHEID are much better than it. It's because Wageningen is great for agriculture and forestry etc. which are probably categorized by QS under development studies. As for IHEID, I think it not being a full university does not let it make the cut. But then same should be the case for Sciences Po so I find IHEID not being anywhere in the QS rankings strange.