mortgage prepayment model

I am trying to develop my own MBS prepayment model. I am confused by the terms SMM and CPR. Are they estimates/models in themselves or are they ACTUAL data for the MBS pool. where can I find actual historical MBS prepayment data?

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Are you looking for commercial or residential data? –  jeff m Sep 14 '12 at 13:22

SMM stands for single-month mortality and CPR stands for constant (or conditional) prepayment rate. They're both units of voluntary prepayment rates ($CPR = 1-(1-SMM)^{12}$). They could be based on either estimated or actual prepayments.