The research team at Henley Management College knew it would not be easy to pin down the apparently nebulous concept of emotional intelligence.
Daniel Goleman's work was a good starting point, but co-researchers Victor Dulewicz and Malcolm Higgs felt it would take more than a well-written book to establish the validity of arguments suggesting EQ was the magic ingredient for success in business and in life.
What was needed, they decided, was some kind of EQ test, backed up by research into the characteristics of emotional intelligence that could be identified and measured.
Luckily, they had already conducted an in-depth longitudinal study of the progress of 100 managers who were assessed on the Henley general management course in 1988-89.
The researchers matched the skills of these managers against Goleman's definitions of emotional intelligence and against IQ scores. They found that those highest on the career ladder had the highest levels of "emotional competence". The most successful were those with both a high level of EQ and above average IQ.
The researchers then took this work one step further by defining 12 competencies, labelled as "MQ", which they believe are key attributes of successful managers.
The study has culminated in an EQ test piloted among 200 managers at Henley. The details are still closely guarded, but the test looks for evidence of seven sets of skills and personality traits. They are self-awareness; emotional resilience - managing feelings when expectations are thwarted or challenged; motivation; interpersonal sensitivity; influencing others; decisiveness - especially when faced with incomplete or ambiguous information; conscientiousness, integrity and ethical behaviour.
Dr Higgs said: "The view we have come to is that EQ is the overarching concept. It is really a question of balancing all of these qualities, some of which may be pushing you in different directions at any one time."
The detractor Stefan Wills, psychologist and programme director at Ashridge Management College, is unhappy about the term "emotional intelligence" and opposes the idea of an EQ test.
"It leads us back into some of the traps we fell into over the IQ debate. Just using the word intelligence puts me off - it makes us obsessed with trying to define it and then everyone wants to measure it."
His preference is for a more loosely defined concept, which he calls "emotional creativity". This, he says, is all about how people express or suppress their emotions in everyday life and in the business environment.
"Some people repress their emotions; some express them chaotically, which is when something like anger comes to the surface; and others express them creatively - which, of course, is the way to go. It is a key concept for effective leadership: you have to understand yourself emotionally before you can deal with the emotions of others and the emotional 'feel' of an organisation," he says.
The great thing about emotional creativity, he adds, is that it can be learned. Students on Ashridge's four-week general management programme are introduced to the concept, and asked to think about applying it in the workplace. There are also emotional creativity workshops, which have proved popular with leading companies.
Wills says: "On a one-to-one basis you can help people see their emotional self, thinking back to the critical times in their lives. They are then better equipped to deal with their personal and professional lives. I don't think it is a fad - companies are taking it very seriously."