Market Research - Future Population Growth Accuracy / Value

[Cory Tuck]

I am in the process of completing some market research for turnkey investments.  I was wondering what sources of data are the most accurate in predicting future population growth for a metropolitan area.  

The second question is this metric useful for guiding future value appreciation predictions for mid-market turnkeys.  For example if I knew Memphis, Kansas City, Indianapolis were projected to grow at 5% per year, would that figure be useful or are the cities so large that a holistic figure like this has limited use.