Case-Shiller: A Warm Winter for Home Prices

It’s time (a bit past time, actually) for our monthly check-in of the S&P/Case-Shiller Home Price Indices (HPI). The Case-Shiller data is generally considered to be the most reliable measure of overall home price changes for a region, since they only consider repeat sales of homes when calculating their index, instead of looking at all the homes that sold in a given month.

For the full source data behind this post, hit the S&P/Case-Shiller website. For a more detailed explanation of how the Case-Shiller Home Price Index is calculated, check out their methodology pdf. Also remember that the data released on the last Tuesday of a given month is for the period two months prior (i.e. – December data is released in February).

Here are the basic Case-Shiller stats for the Phoenix area* as of January:

January 2012
Month to Month: Up 0.9%
Year to Year: Up 1.3%
Prices at this level in: April 2000
Peak month: June 2006
Change from Peak: Down 40.6% in 74 months
Low Tier: Under $101,282
Mid Tier: $101,282 to $176,329
Hi Tier: Over $176,329

Sixteen of the twenty metro areas tracked by Case-Shiller saw a decrease in their HPI between December and January (one less than between November and December): Washington DC joined Phoenix and Miami with an increase. No data was available for Charlotte in January. Oddly, San Francisco had the largest drop at 2.5%.

Here’s a look at the latest local tiered data, back through 2000:


And here’s a closer look at the recent changes, with the vertical and horizontal axes zoomed in to show just the last year:


All three of Phoenix’s tiers rose in January. Month to month, the low tier was up 1.4%, the middle tier rose 1.2%, and the high tier increased 0.5%.

In this next chart, I’ve visualized the month to month trends of all twenty Case-Shiller-tracked cities. Green and above the horizontal axis if they were increasing in the month charted, red and below the axis if they were decreasing. I’ve excluded 2000 through 2004 since they looked largely the same as 2005 (mostly green).


Another gain here, with the best January showing since 2006, when 11 markets were increasing.

Here’s a chart of Case-Shiller HPIs for all the markets that Redfin serves:


Here’s our peak decline chart, in which we line up the peak Case-Shiller HPI value for each of Redfin’s markets, so we can see how long each market has been declining, and how much it has dropped from the peak.


Eight cities hit new post-peak lows in January: Tampa (not shown above) at 47.9% off peak, Atlanta at 37.4% off peak, Chicago at 35.9% off peak, Las Vegas at 61.6% off peak, New York at 25.3% off peak, Cleveland (not shown) at 22.4% off peak, Portland at 30.3% off peak, and Seattle at 32.4% off peak. The 10-city and 20-city composites both also hit new lows, both at 34.4% off peak.

Methodology: The Case-Shiller index tracks price changes in sets of homes of similar size and style to better determine changes in what people are willing to pay for the same home over time. If data is available from an earlier transaction for the same home, the two sales are paired and treated as a “repeat sale.” Repeat sales that are too far apart, sales between family members, lot splits, remodels, and property type changes (e.g. from single-family to condos) are excluded from the calculations. All remaining repeat sales are totaled together and weighted based on the time between each sale, then the data for the most recent three months is averaged together to create a given month’s index value (i.e. – September’s index represents the average of the data from July through September).

The three price tiers plotted in the charts below simply represent the top, middle, and bottom third of all sales, based on the initial sale price. In other words, if there were 3,000 sales in the three-month period, 1,000 of them would be in the low tier, 1,000 in the middle tier, and 1,000 in the high tier, by definition.

*[Case-Shiller defines Phoenix as the Phoenix-Mesa-Scottsdale, AZ Metropolitan Statistical Area, which includes all of Maricopa and Pinal counties.]