@Joe Villeneuve I get that but, I still think you need to know how the market is doing but looking at statistics, historically via charts as well as knowing your "numbers" 

I say that's a myth and a statistical outlier.  

It is a fraction of a percentage and that is a macro statistic while your handful of flips is micro. 

Me personally I am looking at house values, income relative to city, %renters, population shift, COL index and education statistics. 

I use Trulia.com for crime and other local statistics.

You can look at an area's average statistics and assume that's what your property will perform at.

I have a good understanding of statistics and I feel I understand the valuation methods well, but the methods have all come from the very intelligent people here on this forum with much, much more experience than I have in the rental business.

The list ranks cities using a combination of feedback from people who live and work in the communities and statistics like education, employment, economy, crime, parks, recreation, and housing.

Does anyone know of good websites to find out the market statistics for commercial and industrial real estate? 

The rule is based on a LOT of statistical evidence over time.