You can think of factors as the dominant attributes of the people who care about a particular topic or trend. They represent the range of emotions and mindsets found in the universe of a particular topic/trend.
MotivBase identifies four different ethnographic factors: Motivations, Attitudes, Fears, and Values. The permutations of these factors - the specific Motivations, Attitudes, Fear, and Values that you see tied to a specific topic search - allow MotivBase to explain the culture behind a topic or trend.