The exodus of the middle class could be considered a "pre-pop" of sorts and shows how it has already affected Bay Area residents.When the tech industry deflated in the late 90's, Silicon Valley high-tech industries declined about 17% according to the Bureau of Labor Statistics. 

Statistics show that your mail doesn't truly gain momentum and start to pay off until the 5TH mail piece so consistency is key.

I appreciate your advice and the statistic from the BP Poll.  

I have done some research on my own, looked at crime maps, called the city planning office, looked at employment numbers, rents, income statistics etc. and do plan on checking out the property as well as looking at the area while there.

Actually the use of percentages on the expenses related to income rental properties are usually very accurate measurements based on hundreds of thousands of rental property statistics.

But if you disregard all that time+money invested, then yes, being a doctor will statistically give you the highest pay on average. 

Check the specific homes' tax payment, the neighborhood, other public records.Now, I spend time to run statistics of the MLS data to see what is a price range I can consider.

Does that statistic hold true for your rentals? 

Yes, there is a risk that their value quickly falls in a market crash, but I feel that statistics are on my side, and that I can make up for that risk by having a large amount of money in relatively liquid index funds.

Not sure what the statistics are on abandoned buildings, but there's way too many.