At Forbes, Mary Frakes and Thomas Harrison teach us about five personality factors they say are key in assessing whether one has the necessary makeup to be a successful entrepreneur.  The first four may seem obvious:

Openness to Experience

Conscientiousness

Extroversion

Agreeableness

The fifth personality factor stands out a bit: Neuroticism.  Here's how Frakes and Harrison introduce this trait:

This one's a biggie. Neuroticism measures how strongly and negatively you react to the stresses of life. Highly neurotic people have strong emotional reactions to problems and take a long time to get over bad moods, anger or hostility. They often feel anxious or depressed, and are seen as worriers. Those at the other end may not always be happy or cheerful, but they don't tend to be overwhelmed if they occasionally feel depressed, anxious, or angry. Such equanimity gives them an advantage as entrepreneurs because they tend not to let snags get them down.

Frakes and Harrison provide a quiz that examines one's neuroticism, and the other 4 factors, as a means of determining whether one is better suited to work in a company or for herself/himself.  Take the quiz here, and then read more on the methodology here.