July house prices gained 8.1% from the same point last year, slowing somewhat from the 8.8% growth measured in June as the effect of the homebuyer tax credit begins to fade, according to data provider Clear Capital. Clear Capital's Home Data Index Market Report tracks housing prices along a rolling quarter-by-quarter basis. July house prices increased 7.9% from the previous three months, an improvement from the 5.2% growth seen in June. Alex Villacorta, senior statistician at Clear Capital said home prices are continuing their growth from the beginning of the year. "This trend indicates that the initial upward momentum created by the tax credit expiration is being sustained," Villacorta said. "While quarterly gains are showing strong momentum across the country, these recent price advancements are just the latest turn in a volatile housing market that has seen 'W' shaped price trends over the last two years." Morgan Stanley analysts warned that data from these large indices should be taken with a grain of salt as local markets can deviate from one another despite larger macro trends. Scott Sambucci, vice president of data analytics at Altos Research, brought up similar concerns when he predicted further declines through 2010. But Clear Capital did see different performance in separate regions of the US, particularly in the West, which has seen "sustained growth since the trough of the downturn in the first quarter of 2009," Villacorta said. Prices in the West have been stable compared to rest of the market, increasing 2.7% in July. It has bounced between a 1.6% drop to the latest gain in July since the start of 2010. On the metropolitan statistical area (MSA) level, Charlotte, North Carolina demonstrated more stability than the nation, much like the West. Prices there declined only 13% since its peak in the middle of 2007, while, national prices have dropped more than 30% since its height in the middle of 2006. Despite the up-and-down behavior, national prices are still up 13.6% from Q109, Villacorta said, "providing a cushion against potential future declines and the start of a double-dip." Write to Jon Prior.