There was a time when Marketing based on a lot of research and many times when the final arrow was shot it was done a lot of guts and faith, but that has changed in the recent times. Now Marketing in any company depends tremendously on data received from online properties.
Though there is a catch that you might get dumped with so much data, the key is to churn the data to find matrices that give you visibility. Marketing in my opinion has become so much more informed than before and so much more complex that before.
It is a Data and Decision game where your performance as a marketer is also in close scrutiny whether you like it or not.