How do I measure a market's flip rate?

[Brady Grohne]

It seems to me that the flip rate, i.e. the percentage of home sales that are flips, can be a useful measure in taking the "temperature" of a market and as a supply/demand indicator. But, what is the best source for this data point? Alternatively, what is the best practice for calculating this rate from raw data? Most of the studies that I find posted are too old and/or too general to have any relevance. Thanks!