About 15 percent of Ventura County schools rank in the top 10 percent statewide for student test scores, according to rankings released Wednesday by the California Department of Education.

That's about the same percentage of county schools that made the top tier last year. Also similar to last year's rankings, fewer than 1 percent of Ventura County schools scored in the bottom 10 percent statewide.

The rankings, known as the Academic Performance Index, were based on student scores on standardized tests mostly taken in spring 2007.

Schools receive a score based on a scale of 200 to 1,000, with 800 the target. They were ranked in two categories, on a scale of 1 to 10.

The first ranking compared their scores with all other schools in California. The second compared schools with similar demographics, such as family income and the number of students still learning to speak English.

"I think they are very helpful for schools," state Superintendent Jack O'Connell said Wednesday of the rankings. Educators can now easily identify the top schools and learn from them the best ways to improve student achievement, he said.

In the Ventura Unified School District, Superintendent Trudy Tuttle Arriaga said she looked at Wednesday's rankings and compared them to several years ago.

"We are very pleased," she said of the improving schools, including Sheridan Way and De Anza, an elementary and middle school on Ventura's west side.

Those campuses still have two of the lowest scores districtwide, and when compared with schools statewide, Sheridan Way ranked a 3 and De Anza a 4. But both schools, which have a high percentage of English learners and low-income students, did much better when compared with campuses of similar demographics. De Anza, for a second year, was in the top 10 percent of similar schools.

It's exciting to see the results, Arriaga said, but it's just one of numerous indicators of a school's performance.

Along with the rankings, state officials released the 2007 Base API score and 2008 target scores. The targets are what districts, schools and all categories of students will have to meet on tests that students have been taking over the past several weeks. Those results will be released in August.

Highlights from Wednesday's results include:

n Five Ventura County high schools earned 10s when ranked against all other schools: Foothill Technology, a magnet school in Ventura; Santa Susana, a magnet school in Simi Valley; Oak Park; Thousand Oaks; and Westlake. Foothill, the top scoring high school at 904, was the only one to also receive a ranking of 10 when compared with schools of similar demographics.

n The Oxnard and Rio elementary school districts posted some of the lowest scores, with eight of their campuses ranked in the lowest 10 percent statewide.

Those schools, however, ranked higher when compared with those of similar demographics. Teachers and administrators are using intervention programs that target students' specific needs, said Micheline Miglis, district program improvement administrator, and the district is seeing significant overall growth in test scores.

n Some schools that have consistently scored high in statewide rankings did not do as well when compared by demographics. Meadows and University schools in the Conejo Valley Unified district and Red Oak School in Oak Park Unified earned 9s in statewide rankings but only 3s in similar-school rankings. Medea Creek Middle School in Oak Park got a 10 and 3.

Some officials believe the statewide rankings are a better indicator of quality than the demographic rankings. "One of the outstanding things in our district is the quality of education that we have maintained over time," said Laurel Ford, Oak Park's director of teaching and learning.

n Six schools in the Las Virgenes Unified School District, which includes Westlake Village, Agoura Hills and Calabasas, scored above 900. Twelve of the district's 13 schools were ranked in the top 10 percent statewide, and all ranked in the top 20 percent.

For a complete list of the rankings, visit http://www.cde.ca.gov/ta/ac/ap/apireports.asp.