The key to home prices in these uncertain times is supply, and the key to supply is foreclosures. More foreclosures mean an increase in supply, which mean a decrease in prices. But foreclosure numbers are a closely held secret.

Foreclosure information isn’t available like home appraisals or even home sale prices. You can’t pull up a website or check a database or call an expert, and there aren’t lists and charts to fit into a spreadsheet. Rather, the information is filed in the Dallas County courthouse, where a foreclosure sale is held on the first Tuesday of each month. And even then, the documents, called a Notice of Substitute Trustee Sale, don’t actually represent a foreclosed property. It’s an intent, and the lender could change its mind, work out a deal with the homeowner, or sell the loan to someone else.

All of which means that we have almost no way of knowing if the 100 or so homes posted for foreclosure in Dallas in August when I checked last month were foreclosed. Which means we’re missing some valuable information for our six-month update to the Advocate Home Price Snapshot, first published in January. The snapshot, compiled with yeoman assistance from Coldwell Banker’s Ron Burch, tracks home sale prices in the 20 ZIP codes where we publish magazines.

The overview? The situation isn’t as robust as it was in January, when 2007 sale prices were up for the fourth consecutive year in seven of the eight ZIPs. But it’s still nowhere near as bad as it is in the rest of the country. And, said a couple of experts I talked to, if we haven’t seen the worst of the housing downturn by now, we probably won’t.

Home sale prices rose in the first six months of 2008 in 11 of the 20 areas we looked at and declined in the other 9 — and in no apparent discernible pattern. In the eight ZIP codes in East Dallas, Lakewood and Lake Highlands, three saw higher prices and five saw lower prices. The average sale price for the 289 homes sold in 75214, for instance, fell to its lowest level since 2005, while the price of the 143 homes sold in 75206 increased another five percent over what was already a 41 percent increase from 2003.

A couple of thoughts, based on what I saw in the statistics and what I gleaned from the experts:

• We’re not seeing the foreclosure numbers here that they’re seeing in the Mid-Cities, Collin County and other parts of Tarrant County. George Roddy, who tracks foreclosures, says the hardest hit areas in Dallas are southern Dallas County. Most of the 11,517 homes posted for foreclosure in Dallas County this year aren’t around here.

• Days on market increased in six of our eight ZIP codes, and some by significant amounts. It was up one-third in 75204, 22 percent in 75206, and 19 percent in 75218. These still aren’t lengthy waits, though; mostly around three months.

• There are more homes on the market in every area, based on percentage, for the first six months of this year compared with last year. It looks like we’re trying to lock in our profits and take advantage of depressed prices elsewhere.

• The percentage of homes that sold decreased, based on percentages, in the first six months this year compared to last year. In 2007 in 75206, about one-third of the homes for sale sold; this year, it’s just 25 percent. In 75204, the numbers were 41 percent and 20 percent.

So where does that leave us? Glancing nervously over our shoulders, waiting to see how much worse the economy gets. The conventional wisdom is that we haven’t suffered as much as elsewhere because our prices didn’t increase as much as elsewhere, but the worst performing areas through June 30 in East Dallas and Lake Highlands are the two with the least expensive homes and the least price appreciation since 2003 — 75223 and 75243.

Which brings us back to foreclosures. My guess is that lower-priced homes equals more creative financing, which equals more foreclosures. Too bad we don’t have an efficient way of finding out.

As always, when I make an error, our readers let me know. In my July column, I referred to pod people from the movie “Night of the Living Dead”. That’s the wrong movie. The pod people were in the original “Invasion of the Body Snatchers”.

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