So what are Southern California appraisers trying to tell us?

These real estate professionals have their own voice in the grand bubble-or-not debate over local home values. Of course, there’s their day-to-day work in the trenches. And their role in an intriguing home-price metric compiled by the Real Estate Research Council of Southern California, headquartered at Cal Poly Pomona.

For nearly three-quarters of a century, the council gets appraisers to reevaluate the same properties every six months – over and over and over again. Yes, looking at roughly 300 homes is a tiny sample of local housing. But it’s also a consistent sample — retooled in 1990 — that minimizes the built-in variables that can plague other indexes based on the ever-changing mix of what’s selling and what’s being built.

To my eye, the collective opinions of local appraisers are always worth noting. And the council’s appraisers’ indexes raise a few questions about Southern California’s post-recession housing appreciation.

So, I used my trusty spreadsheet to compare five years worth of home-price gains by two yardsticks — as measured by the council’s appraisal-based index vs. the widely followed Southern California median selling price, as tabulated by CoreLogic.

Sort of man vs. machine, real estate-style.

The results are quite clear, and not totally surprising to anyone who knows of the skeptical eye of professional appraisers. In five of six Southern California counties, this appraisers’ index showed significantly smaller gains than the upswing in selling prices.

Riverside County was the lone market where both metrics — tracking prices in the five years ended in October — were roughly in sync. Appraisers saw a 73 percent increase in Riverside County values and CoreLogic’s median was up 71 percent.

San Bernardino County had the widest gap between what the human eye saw and what the computers spit out: Appraisers say values are up 59 percent; CoreLogic says 91 percent!

Elsewhere in the region, here’s how the battle-of-the-index gaps shaped up since 2012 …

Los Angeles County: Appraisers say up 58 percent; CoreLogic says 72 percent.

Orange County: Appraisers say up 44 percent; CoreLogic says 55 percent.

San Diego County: Appraisers say up 50 percent; CoreLogic says 56 percent.

Ventura County: Appraisers say up 45 percent; CoreLogic says 53 percent.

Now, these gaps may partially be a reflection of the often-bemoaned shortage of “affordable” homes to buy.

Southern California’s painfully thin supply of homes at the lower-end of the price spectrum has distorted indexes like CoreLogic’s median. These metrics end up reflecting a buyer’s willingness to pay up for the higher-priced housing that’s on the market. This statistical pattern doesn’t mean all home values are up at the median’s skyward pace.

Yes, it’s not totally shocking these appreciation gaps — man-vs.-machine — exist in the first place. Remember, appraisers get paid to be real estate’s party poopers — protecting overzealous lenders from overlending on overvalued properties.

So by nature, appraisers are … let’s say … skimpy! Still, their cautious viewpoint can’t be easily ignored, since they often have the power to kill a prospective home purchase with a low valuation.

Plus, the collective wisdom of appraisers is especially noteworthy as Southern California’s eye-catching home-price gains continue.

PS: Note that Southern California’s housing market is “overvalued,” according to a CoreLogic valuation measure. As of October, the Los Angeles County, Orange County and Inland Empire housing markets were among 37 top 100 U.S. metro areas where home prices were 10 percent or more above the long-term, sustainable level, according to the data firm’s latest Market Indicators Report.

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