Price ratios between distressed and retail sales

[Wes Farmer]

I am reading J Scott's Book on Flipping House's and want to hear some of the forum member's interpretations of Chapter 4 subsection Analyzing Potential Properties "Price ratios between distressed and retail sales". I'm having a hard time figuring out exactly how to find these numbers to calculate a ratio for my area. J mentions a 50% average to look for, but where do I get these numbers to calculate the average? Does this require access to the MLS and if so which search filters should I be using. Its a wonderful book but I'm stuck on the subject of analyzing my potential markets. Any help would be greatly appreciated.