Last week I was driving and heard KPBS's Dwane Brown tell me that San Diego home prices had risen 90 percent over the year.

Um, what?

That was the teaser for a story that came on a bit later, when Brown reported that sales, not prices, had risen 90 percent. The numbers came from the California Association of Realtors.

Still, the number seemed really high. Sales have been going up for the last 11 months, but 90 percent?

I freaked out then, but forgot to look it up when I got back to my office.

Turns out the CAR got it wrong.

This afternoon, a savvy reader e-mailed me a link to a Wall Street Journal story.

I love the headline:

Home Sales Didn't Soar in San Diego: Data Had Errors, Group Says

The group will make "sharp downward revisions" to its recent months' estimates of sales in the San Diego region, according to the story. WSJ reporter Bob Hagerty interviewed CAR's deputy chief economist, Robert Kleinhenz, who said the group will announce its revisions in late July along with the numbers for June sales.

The differences are stark:

The California Realtors have reported that San Diego sales in April were up about 63% from a year earlier. Mr. Kleinhenz said that is expected to be revised downward to a gain of about 20%. For May, the group reported an 89% increase in sales in San Diego; that will be slashed to about 6.5%, the economist said.

That 89 percent is what I'd heard on the radio last week. Turns out that was a little high.

Kleinhenz said the hiccup came from San Diego's MLS, which changed computer systems and has been sending faulty data to the state association over the past year. Here's how they found the quirk:

Thomas Lawler, an independent economist in Leesburg, Va., who tracks home sales nationwide, raised questions about the San Diego data in a report last week. Mr. Lawler noted that the numbers reported by the Realtors vastly exceeded those from MDA DataQuick, a research firm in La Jolla, Calif., and other sources.

— KELLY BENNETT