Writing on Barry Ritholtz’s The Big Picture blog, real estate and mortgage researcher Mark Hanson has a different view of what a 0.5% rise in Case-Shiller’s quarterly report on home prices means.

Background: That half-percent year-over-year rise is the first one since September 2010, and that’s good news, especially because every market Case-Shiller surveys saw price gains.

But Hanson has a different view. His take is that even this small across-the-board gain is exaggerated.

When you (or, rather, when Case-Shiller) compare July 2012 to July 2011, you’re comparing today’s figures with the “severe hangover period from Feb to April 2011.” (July closings = February to April contracts, you see.)

Why the hangover? Because that was just following the home buyer tax credit. Hanson believes that the credit drove sales and prices (artificially) up, and the expiration caused a “hangover” that drove them (artificially) down.

Thus, comparing July 2012 to July 2011 gives you an overly optimistic number. And if 0.5% is optimistic… well, that doesn’t bode well for the reality behind it.

Add to the mix 1) the fact that low interest rates mean people today have a lot more purchasing power, and 2) distressed sales are a much smaller part of the market, and you would think today’s number would be higher.

As Hanson put it

a YoY 15% increase in purchasing power and 25% decrease in foreclosure resales and still the [Case-Shiller price index] only managed a 0.5% gain over last year.  To me, normalized, that means real house prices are still falling.

Of course, his argument is predicated on there being an unnatural slump in July 2011, and that’s hard to be sure of. Yes, July ’11 numbers were lower than July ’10 because of the 2010 tax credit. But how much of a post-tax-credit ‘backlash’ was there in 2011? You can’t say what would have happened.

Which is why I’m not entirely convinced by Hanson. Was July 2011 a normal year, an artificially lower year, or maybe even an artificially higher one? The answer to that question (which can’t be answered) tells you whether today’s numbers are too hot, too cold, or just right.