The median resale price of single-family homes on O'ahu this year has been fairly stable with slight appreciation, but many submarkets on the island have not fared as well.

Median prices dropped in nine of the 17 O'ahu housing regions defined by the Honolulu Board of Realtors in the first eight months of the year.

The breakdown illustrates the industry mantra that all real estate is local.

"Some of the market probably did some overshooting, so I would expect some pullback from that," said local economist Mike Sklarz.

In general, median prices have weakened in urban Honolulu, East O'ahu and Leeward O'ahu, while median prices are higher in Central and West O'ahu.

The biggest median price drops were on the Windward Coast and North Shore at about 10 percent. Other softening markets — Honolulu, 'Aina Haina-Kuli'ou'ou, Hawai'i Kai, the 'Ewa Plain and Makakilo — had median price drops of roughly 2 percent to 4 percent.

Waipahu and Moanalua-Kalihi had median price dips of about a half-percent, while the Pearl City-'Aiea median was 0.1 percent, or $500, higher.

Posting higher median prices of 2 percent to 8 percent were Kapahulu-Diamond Head, Wai'alae-Kahala, Kailua-Waimanalo, Kane'ohe, Wahiawa and Mililani.

According to Honolulu Board of Realtors statistics, median resale prices from 2003 to 2005 rose in all of O'ahu's 17 single-family home regions defined by the trade association.

Last year, only two of the 17 regions suffered median price declines — a 7.7 percent drop for 'Aina Haina-Kuli'ou'ou and a 1.3 percent dip for Kailua-Waimanalo.

This year through August, however, median price declines spread around the island to nine of the 17 regions, while O'ahu's overall median sale price is up 1.9 percent to $647,300.

"The valuations are basically treading water," said Paul Brewbaker, chief economist at Bank of Hawaii. "Some may be backtracking, and some still have lift."

For condominiums, spread over 19 regions, year-to-date median prices were lower in only four areas — Hawai'i Kai, Wahiawa, the 'Ewa Plain and Makakilo. Overall, O'ahu's median condo price is up 4.8 percent to $325,000.

It should be noted that not all regional median price moves reflect an across-the-board change in home value.

The median price is a point at which half the sales were for more and half for less. Median price changes can be driven or magnified by the mix of homes sold within an area. For instance, if a greater proportion of older homes sell in a region, that could weaken the median price. Likewise, if a greater proportion of larger homes sell, that could boost the median price.

In Kaka'ako, a boom in luxury high-rise construction in the last few years produced lots of million-dollar condos and helped push the area's median price up to more than double this year.

STATISTICAL SKEWS

Relatively few sales in a market also can sway median prices. For instance, one of O'ahu's smallest submarkets, Wahiawa, had 55 sales and the second-highest median price gain at 5.9 percent. The North Shore had the biggest median price decline at 10.6 percent on 70 sales.

Still, the data suggest that home values in some markets, such as 'Ewa Beach, have pulled back following their roughly doubling from 2001 to 2006.

Sklarz, who is president of Tokyo-based investment banking and development firm New City Corp., calculated median prices per square foot of living space as a way to filter out deviations from sales of bigger or smaller homes.

Sklarz found that the median price per square foot is down in 'Ewa Beach, consistent with the Honolulu Board of Realtors' data for the larger 'Ewa Plain.

But the price per square foot is flat in Hawai'i Kai and down in Kane'ohe, in contrast to the Realtors' data showing a decrease for Hawai'i Kai and increase for Kane'ohe.

Harvey Shapiro, a research economist with the Honolulu Board of Realtors, said it's not clear whether median price changes are more a result of shifting values or the mix of homes sold.

"I'm not sure that there are value changes there," he said. "It could be mix-related."

Shapiro said the broad geographic distribution of median price ups and downs is a positive sign for the market.

"There's no geographic trend here," he said. "I think that's a good indicator that O'ahu housing is stable."

DETAILS FUZZY

Typically, when prices begin to rise, higher-end markets tend to be affected first, and lower-end markets follow. Conversely, prices in high-end neighborhoods tend to soften first in a weakening market. But this hasn't been the case over the past eight months on O'ahu.

The median price in the island's second-priciest market, 'Aina Haina-Kuli'ou'ou, is down 4.3 percent to $950,000 on 49 sales, which follows a 7.7 percent drop last year. In Hawai'i Kai, the third-priciest market, the median price is down 2 percent to $872,000 on 162 sales.

Yet O'ahu's priciest market, Wai'alae-Kahala, has a year-to-date median price that's up 3.7 percent to $1.39 million on 101 sales.

A mix of higher and lower median prices is also occurring in more affordable regions.

O'ahu's most affordable area, Makaha-Nanakuli, has a year-to-date median price that's up 7.7 percent to $378,500 on 145 sales. The median price in O'ahu's second most affordable area, Wahiawa, is up 5.9 percent to $490,000 on 55 sales. But the 'Ewa Plain, O'ahu's largest submarket and the third most affordable, has a 1.8 percent median price decline to $520,000 on 421 sales.

Cecilio Riodil, broker in charge at the Waipi'o Gentry office of Century 21 Homefinders of Hawai'i, said he's not surprised that a market like the 'Ewa Plain is seeing slightly weaker median prices, because inventory is higher and sales are lower.

"It might continue to slide a little bit more, unfortunately," he said.

Reach Andrew Gomes at agomes@honoluluadvertiser.com.