Home prices started the year on an upswing. 

According to the Federal Home Finance Agency’s Home Price Index, home prices rose by a seasonally-adjusted 0.3 percent between January and February 2012. The index is up 0.4% over the past year, offering a counter-story to the Case-Shiller Index’s assertion that home values are sinking.

Last week, Standard & Poor’s Case-Shiller Index said home values had dropped more than 3 percent in the prior 12 months. 

As a home buyer or seller in Los Angeles , data showing “rising home values” or “falling home values” may be of interest to you, but we can’t forget that most home valuation trackers — including both the government’s Home Price Index and the private sector Case-Shiller Index — have a severe, built-in flaw.

Both used “aged” data. Today, the calendar reads May. Yet, we’re still discussing February’s housing data.

Data that is two-plus months old is of little value to everyday buyers and sellers wanting to know the “right now” of housing. And, even then, characterizing the data as “two-plus months old” may be a stretch. This is because the home values used in the Home Price index and the Case-Shiller Index are collected from actual transactions, but at the time of closing.

Considering that most purchases require 45-60 days to close, we can know that when we look at the Home Price Index and Case-Shiller Index reports for February, what we’re really seeing is a snapshot of the housing market as it existed two-plus month plus 60 days ago.

Data that’s 5 months old is of little relevance to today’s buyers and sellers. Today’s market is driven by today’s economics.

The Home Price Index is a useful gauge for economists and law-makers. It highlights long-term trends in housing which can be helpful in allocating resources to a particular project or policy. For home buyers and seller throughout California , though, it’s much less useful. Real-time data is what matters to you.

For that, talk to a real estate professional.

The government is confirming what the private sector has already shown —  home values are on the rise.

The Federal Home Finance Agency’s Home Price Index shows home values rose 0.8% in July.

July marks the fourth straight month that home values climbed and the FHFA’s Home Price Index is the latest in a series of “rising home values” reports — an encouraging trend for buyers and sellers in San Francisco and nationwide.

Last week, the S&P Case-Shiller Index showed home value up nearly 1 percent in July. CoreLogic reached a similar conclusion.

Nationwide, values are back to their highest levels since November 2010. Clearly, the housing market in California is moving in the right direction. Or is it?

Although the data from the government and from private firms such as CoreLogic is encouraging, it’s also flawed. As such, we have to be careful about the conclusions we draw from the data.

The flaws of Home Price Index are glaring :

1. Only homes backed by Fannie Mae or Freddie Mac are included in the index. In today’s market, because of the FHA’s popularity, that leaves 1 of 3 homes “uncounted”.
2. Only home resales are counted. New home sales are omitted entirely.
3. The data comes with a 60-day delay. The October market is different from July’s.

Despite these shortcomings, however, the Home Price Index remains relevant. It’s among the most through home valuation models and it’s often used by economists and policy-makers.

When the Home Price Index is rising, Wall Street and Capitol Hill take notice. For residents of “Main Street”, however, the data may not be as important. To get local, up-to-date market statistics , talk with a professional real estate agent.

Since peaking in April 2007, the FHFA’s Home Price Index is off 17.6 percent.

Earlier this week, the private-sector Case-Shiller Index showed home prices slightly lower between November and December.  Thursday, the public-sector Home Price Index showed the same.

Publishing on a 2-month lag, the Federal Home Finance Agency said home prices fell by 1.6 percent nationally in December.  And that’s an average, of course.  Some regions performed well in December as compared to November, others didn’t.

• Values in the Middle Atlantic states improved slightly
• Values in New England were essentially unchanged
• Values in the Mountain states sagged, down 3.5%

These aren’t just footnotes. They’re an important piece toward understanding what national real estate statistics really mean. In short, “national statistics” are just a compilation of a bunch of local statistics.

For example, if we dig deeper into the FHFA Home Price Index 70-page report, we find that cities like Terre Haute, IN, Buffalo, NY, and Amarillo, TX posted year-over-year home price gains. You won’t see that in a “national” report.

Furthermore, it’s a sure bet that those same cities, you could find neighborhoods that are thriving, and others that are not.  Just because the city shows higher home values overall, it won’t necessarily be the case for every home in the city.

Every street in every neighborhood of every town in America has its own “local real estate market” and, in the end, that’s what should be most important to today’s buyers and sellers.  National data helps identify trends and shape government policy but, to the layperson, it’s somewhat irrelevant.

So, when you need to know whether your home in Los Angeles is gaining or losing value, you can’t look at the national data.  You have to look at your block — what’s selling and not selling — and start your valuations from there.