Do not work blind.  It is dangerous.  You can hit yourself, stab a friend, or even fall off a cliff.  Doing Marketing without Analytics, is working blind.  Imagine running an ad without measure its effect.  Imagine building a product, without any user input.  Imagine running a TV ad without any information about who watches it, what your goals are, or how to measure those goals.

My approach: Hypothesize, Test, Measure  –>  repeat.