Many social scientists have studied the phenomenon of success. One American study claims that your social network is the key to success. Apparently, every extra friend that you have at school adds two percent to your salary later in life! Perhaps this boosts your self-confidence or perhaps you have more people to support you. Another study links height and success: every extra centimetre is worth another $300 per year. The trouble is that for every person who conforms to these theories, there is an exception