Intelligent leaders

This week's issue of the Economist has a letter from a professsor at HEC Lausanne

It might interest you to know that not a single serious study has ever been able to demonstrate a link between “emotional intelligence” and leadership effectiveness. The most robust and consistent single predictor of leadership effectiveness is, simply, intelligence. Emotional intelligence sells well, but scientific evidence supporting it is almost as solid as that supporting the effectiveness of homeopathy.

I don't know the details of the studies which led to this conclusion, but I wonder if they suffered from a version of the Sample Selection Bias described by Michael Stastny at Mahalanobis. Tyler Cowen once referred to a paper by Shane Frederick to the effect that

Expressed loosely, being smart makes women patient and makes men take more risks

Most senior managers are men. Intelligent men take greater risks than less intelligent men. Men who take risks will be either exceptionally successful or spectacular failures, while men who avoid risks will perform middlingly. If there is Sample selection bias, it will then appear that intelligence correlates with management ability. Just thinking aloud.