The steady rise in house prices has slowed recently, but the decline has yet to be reflected by indicators like the S&P's Case-Shiller indices, writes Bill McBride on his blog Calculated Risk.

The Case-Shiller Home Price Indices lag behind other indicators like agent reports and asking prices because of a reporting lag and because the CSI uses figures that are an average of the previous three months (the August report, McBride writes, was an average of June, July and August prices).

Higher mortgage rates and a slight increase in the number of houses available on the market are responsible for the slowing rate of growth, McBride writes.  

One reason for this misinterpretation is the Case-Schiller Indices insistence on presenting nominal value instead of the real value. The real value is the price adjusted for inflation, so a $200,000 house in the year 2000 would have a real value of $276,000 in today’s dollars.

When viewed through the lens of real value, house prices are at about the same level they were in the early 00s, rather than the mid-00s like the nominal values, when compared, would suggest, he concluded.