Can subjects studied in Master and PhD be different? I am in the middle of my master studies in math and need to decide which subject I want to choose for my master thesis, geometry or statistics. I have the following questions:


  Is it possible to start the PhD (say in statistics) in a different subject as the master/master thesis (say in geometry)?
  
  What actions would you recommand, if I want to change the subject? (e.g. first taking a job in statistical area before starting a PhD in this subject)
  
  Would it make sense to do another master in statistics?


I thought going from the more theoretical subject geometry to the more applied subject statistics more "natural". 
Note that I have in both subjects, geometry and statistics, at least 30 Credits, but my studies (also my Bachelor) is more focused on geometry.
There is a self-evident answer, - yes, it's possible, no any official restrictions, no one care (maybe, except your advisor). 

And there are obvious consequences when you're changing the research topic - you're starting something new with less experience. This can be good or not, and this is your, and only your decision.