"the strongest leaders were best characterised by dominance"

I think this too can be viewed as the strongest leaders are best characterized by being able to maintain control / manage a situation toward a required direction; It's of course easier to do this if you want to be domineering, so that would create a statistic that shows more 'strongest leaders' as those who are domineering, merely because it's the easier way to do something - but takes much less and skill and nuanced behaviour and understanding.