found a research field in computer science, where do I start ..?

C

Hi,
I managed to speak to a few supervisors at a university and finally have decided to narrow it down to information retrieval evaluation ( suggested by the supervisor). Ok, so the thing now is..its Phd..and its slightly different than masters. But how and where do I start, I suppose I have to at least know what I plan to write on, as I would have to write the proposal. Right now, I am searching on research topics in IR evaluation..what else would help..?

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