Rhode Island’s housing market continued to weaken in October, with prices showing double-digit declines from a year ago, according to a report by a Boston-based real estate market research company.

The median price of a condominium in October was $225,000, down 12.2 percent from October of last year, according to The Warren Group. Condo prices in the state have now declined for three straight months. Prices of single-family houses also fell, albeit less sharply. In October, the median price of a single-family house in the state was $262,500, a decrease of 4.2 percent from October of last year.

“Our figures continue to show sluggishness throughout the Rhode Island housing market,” a news release from The Warren Group quotes its chief executive, Timothy Warren Jr., as saying. “While we’ll be looking closely for signs of bottoming out, our best guess is that we won’t see conditions turn around in a tangible way much before the middle of 2007.”

The nationwide slowdown in the housing market has recently weakened demand for condominiums, which had found strong appeal among first-time homebuyers and homeowners looking to downsize, Warren said in an interview. But as the market weakened, he said, “the effects of gravity finally caught up with them.”

Rhode Island’s single-family house sales during the first 10 months of this year were down 8.85 percent, compared with a 3.6-percent decline in condo sales. Although condo prices have fallen for the last three months, they are still up 5.5 percent since January, the company reported. Condo sales spiked 8.8 percent in October, but Warren cautioned that the October sales numbers are so small that it’s best not to read too much into the one-month increase.

Sales of single-family houses, by contrast, fell 10.31 percent in October compared with the same month last year. Sales of single-family houses have declined for four of the last six months.

The Warren Group is the publisher of The Commercial Record, Banker & Tradesman and other trade magazines. The company’s data is based on public records and includes houses sold by owners as well as real-estate agents.

Rhode Island’s housing market has held up better than the market in Massachusetts, where single-family house sales during the first 10 months of this year have plummeted 15.13 percent, while condo sales declined 13.57 percent, according to The Warren Group.

The median price of a single-family house in Massachusetts in October was $312,000, down 6.87 percent from October of last year. The median price of a condo in October was $261,750, down 4.82 percent from the same month last year.

“You never know where the bottom of the market is,” Warren said, “until you’re at the bottom.”