Effective leaders are alike in one crucial way: They all have a high degree of what has come to be known as emotional intelligence. It's not that IQ and technical skills are irrelevant. They do matter, but mainly as threshold capabilities ; that is, they are the entry-level requirements for executive positions. But my research, along with other recent studies, clearly shows that emotional intelligence is the sine qua non of leadership.
p. 94 - IQ and technical skills are important, but emotional intelligence is the sine qua non of leadership (1998)