The Standard & Poor’s CoreLogic Case–Shiller Home Price Index, also known as the Case-Shiller Housing Index, is a leading measure of US residential real estate prices, tracking changes in the value of residential real estate, both nationally as well as in 20 metropolitan regions. Based on the original work by economists Karl Case and Robert Shiller, this index has different set reference points, and calculation differences provided in each data set. Multiple Case–Shiller home price indices can be classified into: a national home price index, a 20-city composite index, a 10-city composite index, and twenty individual metro area indices. All house price indexes, especially the Case-Shiller, are barometers not just of the housing market, but also of the health of the broader economy.