Teacher turnover is highest in the Pittsburgh Public Schools' most troubled schools, an education group said in a report yesterday, recommending that the district work to make sure the schools are places where teachers want to be.

A+ Schools, Downtown, had the University of Pittsburgh's Learning Policy Center track about 3,000 teachers from fall 2006 to spring 2009. Data was provided by the school district.

Researchers found that turnover was highest at the 14 or so "most vulnerable" schools, defined as those with weak test scores, the highest poverty rates and above-average disciplinary problems. A+ Schools declined to identify the schools.

In all, the study tracked staffing at 58 schools, which were divided into four groups and labeled "most vulnerable," "somewhat vulnerable," "less vulnerable" and "least vulnerable."

The most vulnerable schools retained 54 percent of their teachers during the research period. The least vulnerable retained 66 percent of their teachers. The 58 schools together retained 59 percent of their teachers during the study.

"When teachers move from one school to another within the district, they most often move from more- to less-vulnerable schools," the report said.

The turnover rate at the most vulnerable schools is in line with national trends, but raises questions about whether Pittsburgh is getting "well-supported, committed and effective teachers" at high-need schools, researchers said.

The study also found that the most vulnerable schools had the least experienced teachers, but noted that some researchers have dismissed a link between seniority and effectiveness.

Turnover offers a window on school performance and conditions, said Carey Harris, executive director of A+ Schools.

But not all turnover is bad, she and schools Superintendent Mark Roosevelt said. Some top schools across the country have high turnover because of the heavy expectations placed on staff members, Mr. Roosevelt said.

The study recommended that the district "make vulnerable schools places where teachers can be effective and want to teach. By doing so, the district can manage the effects of mobility so that the most needy students receive the best possible instruction."

Mr. Roosevelt said all teachers should feel comfortable -- and able to do their jobs -- in their assigned schools.

"We're not there yet," he said, noting the district's teacher-effectiveness plan, developed with the Pittsburgh Federation of Teachers leadership and partly funded by a $40 million grant from the Bill and Melinda Gates Foundation, may help on a couple of fronts.

The plan includes new steps to ensure order in classrooms and would offer bonuses to top teachers who accept especially challenging assignments, including turnaround roles in troubled schools. Many parts of the plan must be approved by the union membership.

The district closed 22 schools in summer 2006, forcing hundreds of teachers into new roles. A+ Schools' study did not include that turnover; it focused on the period from fall 2006 to spring 2009.

Ms. Harris said some of the turnover during the research period likely resulted from the district's enrollment decline. When enrollment drops, the district cuts positions at some schools, forcing teachers to move to other buildings.

But Ms. Harris said interviews with 24 teachers showed some turnover occurred because teachers were frustrated with tough assignments and a lack of support from principals. Principals have their own frustrations, she said, including a short window for filling some teaching slots before the start of a school year.

A+ Schools recommended that the district start the hiring process sooner so principals have time to attract the right candidates. Currently, positions at the most vulnerable schools are some of the last to be filled each summer, forcing principals to select novice teachers or veterans who lost positions in other schools and have nowhere else to go.

Looking for more from the Post-Gazette? Join PG+, our members-only web site. You'll get exclusive sports content, opinion, financial information, discounts from retailers and restaurants, and more. Our introduction to PG+ gives you all the details.