With releases of both Standard & Poor’s Case-Shiller and the Federal Housing Finance Agency (FHFA) home price indices on Tuesday, the two markers of home values reflected—as they often do—their varying perspectives on the housing market.

While Case-Shiller reported broad-based, if small, monthly declines of 0.1% and 0.2% for its 10-city and 20-city composite indices, the FHFA index recorded a small monthly gain of 0.4% in August.

How can this be? Well, both the Case-Shiller and Federal Housing Finance Agency (FHFA) indices track home values, but they are calculated differently. Case-Shiller focuses on the 20 largest metro housing markets (which are typically more expensive markets) and includes homes purchased with jumbo loans, which can result in more volatile—or at least different--home price changes than the FHFA index.

FHFA’s figures are based on the purchase prices of homes with loans owned or guaranteed by government-sponsored enterprises (GSE) Freddie Mac and Fannie Mae in all 50 states, including home purchases in rural or less constrained markets. Unlike Case-Shiller, which concentrates on individual metropolitan markets, FHFA also looks at home prices by U.S. Census region, which can include several states, an amount of data that can mitigate the highs and lows of home price changes.

(For more detail on how FHFA index is assembled and calculated, click here.)

According to FHFA, the West South Central region saw the greatest improvement in home values in August with a monthly gain of 1.5% for the states of Oklahoma, Arkansas, Texas, and Louisiana. This same region also noted the largest annual gain, with an uptick of 0.8%.

The Mountain region (which includes Montana, Idaho, Wyoming, Nevada, Utah, Colorado, Arizona, and New Mexico) reported a stumble of 0.6% compared to the previous month. This area of the country, which encompasses foreclosure trouble spots such as Phoenix and Las Vegas, also showed the greatest annual drop, with a 7.5% slide in home values.

On an annual basis, the FHFA home price index was off 2.4% in August.

Alison Rice is senior editor, online, at BUILDER magazine.

Learn more about markets featured in this article: Phoenix, AZ.