How credible is Case-Shiller to NYC?

From The Real Deal

NEW YORK — The words may change, but it’s always a variation on the same tune: Every couple of months, someone sings the song of Case-Shiller, the widely cited home-price index. The question for New Yorkers is whether it’s a local theme song.

While there is no question that the Standard & Poor’s/Case-Shiller 20-city housing index is an influential measure of the country’s shifting real estate fortunes, some New York-based number crunchers argue that it says almost nothing about the city’s — particularly Manhattan’s — real estate reality.