A new study finds a key component of effective leadership is surprisingly simple

Typically, when we envision successful leaders, we think of people who are charismatic, who know how to take control of a room, and who are comfortable in positions of power.

In fact, research suggests that extroversion is generally a strong predictor of successful leadership.

Yet a new analysis of 25 studies, led by Dana Joseph, Ph.D., at the University of Central Florida, complicates the idea that simply being outgoing is enough to make you an outstanding leader. Now, researchers say that positivity is key: Generally happy people make better leaders than Debbie Downers.

The analysis zeroed in on the relationship between trait positivity (or the general tendency to respond positively to situations) and several leadership criteria, including leadership effectiveness.

According to the findings, trait positivity was an even better predictor of effective leadership than extroversion or neuroticism (emotional instability). 11% of the variance in leadership effectiveness was due to trait positive affect.

On the other hand, negative affect accounted for 6% of the variance in leadership effectiveness. In other words, the less happy someone was, the less likely they were to be a successful leader.

Interestingly, not all negative emotions were linked to low leadership effectiveness. Those who displayed anger were more likely to be perceived as poor leaders than those who displayed anxiety.

The key link between happiness and leadership effectiveness, the researchers say, seems to be that happy people typically demonstrate a certain management style called transformational leadership.

Transformational leaders are skilled at things like inspiring and motivating their team, stimulating their team intellectually, and mentoring their subordinates. (A popular example of a transformational leader is Nelson Mandela.) Studies have found there's a strong correlation between transformational leadership and leadership effectiveness.

The analysis found that positive affect accounted for over 20% of the variance in transformational leadership. Moreover, that effect remained even after the researchers controlled for extroversion and neuroticism.

Joseph says she suspects that it's simply easier to be a transformational leader when you're a happy person.

"Positive affect allows people to be inspirational, motivational, and respectful of their followers," she says. "For example, when you're giving a speech to a room and you have difficulty being positive, it's difficult to inspire and motivate the audience."

As for the practical implications of the research, Joseph says it's not realistic to say that aspiring leaders should force themselves to be consistently happy for the sake of getting promoted.

Instead, the takeaway seems to be that hiring managers trying to predict which individual will be an effective leader should place greater importance on candidates' overall happiness levels. Joseph says companies can even measure trait positive affect using the same tools that researchers typically use, such as the Positive and Negative Affect Schedule.

Perhaps happiness is something that organizations already value in their leaders on an intuitive level. But given these findings, it would make sense for employers to make trait positivity assessments a more standardized part of any leadership selection strategy.