More than four weeks into the application period, Chicago Public Schools finally laid out the admissions criteria for its vaunted magnet and selective enrollment schools Thursday.

The new policy makes a handful of significant modifications to a complex formula the school district came up with last year, which relies on socio-economics rather than race to determine admissions.

Numbers show that formula resulted in more white students being admitted to the top elementary schools than in previous years. African-American students saw their representation at top schools decrease, both at the elementary and high school levels. The admissions policy was changed after a federal judge ended the district’s decades-old desegregation plan last September.

The new policy unveiled Thursday still divides the city’s students into four different tiers based on the socio-economic characteristics of the census tracts where they live. To determine what tier a particular census tract falls into, the district considers five factors: median household income, the percentage of single-parent households, educational attainment, home ownership and the percentage of households that speak a language other than English at home.

This year, the district will also consider a sixth characteristic: whether a neighborhood’s attendance-area school is low- performing. If it is, that could give students an advantage.

Adding that sixth neighborhood characteristic means the tier designation has changed for more than 86,000 students across the city.

Schools chief Ron Huberman said the goal of the complicated formula is to maintain racial diversity in the schools without actually considering race in admissions.

The district had said last year it would be presenting permanent policy this year, but Huberman highlighted the need to continue to monitor the effects of the admissions policy.

“We may need to tweak it again, it may need to be altered again,” Huberman said. “Until we actually live through it for a year, and we see how it impacts schools. We don’t really know for sure.”

Other changes include:

• A greater emphasis on socio-economic tiers. Last year, 40 percent of selective enrollment seats were given to students based on strict rank-order scores, without consideration for what socio-economic tier they came from. This year, 30 percent of students will be admitted that way; the remaining 70 percent of seats will go to the top-scorers within each tier.  District models show this will mean slightly more seats for African-American and Latino students and fewer places for white students.

• Support for keeping siblings together at magnet schools. In magnet schools, all open seats will go first to siblings. Parents will now be allowed to link magnet school applications of twins or triplets. This will make it easier for same-aged siblings to be admitted to the same magnet school.

• Continued opportunities for students to transfer under No Child Left Behind to top schools. Top-performing students from dozens of the district’s lowest-scoring elementary schools will again be given the opportunity to attend the top high schools. But this year, they will have to apply for the program and test in. The district will target these students through a special recruitment campaign.

• Safeguards to keep schools from re-segregating. This is the first provision of the policy that actually takes race into account. If a magnet school enrolls more than 50 percent of its students from any one race, and 50 percent of the school’s students also live nearby, a safeguard is triggered, and the lottery held that year will not include a preference for neighborhood children.

• Fraud provisions. Families will now have to verify their address before enrolling. If they move between the time they apply and the time they enroll, they must prove they lived at the application address or the application is voided. Principals at elementary magnet schools will not be given discretion to admit students.

Despite going through meticulous calculations and modeling showing the effects of particular changes, the district said it will still allow principals at selective enrollment schools to set minimum cut scores. Those cut scores last year resulted in fewer students being admitted from the most disadvantaged socio-economic tiers.

Many of the changes were recommended by a blue-ribbon panel of educators and activists that looked at the effects of the district’s policy last year. Among them was Mary Davidson, who served as a monitor for the district’s desegregation plan for a decade in the 1980s. At that time the desegregation order included provisions forcing the school system to provide compensatory services at racially isolated schools.

Davidson hadn’t been involved in desegregation issues for 20 years, and she said it put a knot in her stomach to return to find so many of the city’s children still attending racially isolated schools.

“I said, ‘How can we have these same conversations that we had 20 years ago?‘” Davidson said. “I came back to this surprised that we had abandoned the racially isolated schools—that part of the [desegregation] plan. And we were focusing solely on selective enrollment—really, very few seats for thousands of children.”

But Davidson says she is heartened by what she perceives to be the district’s commitment to keeping integrated CPS schools racially diverse. The panel will re-convene next year to track the effects of this new policy.

The Board must still approve the policy and is inviting public input before then on its website. The Board is expected to vote on the policy at a Nov. 17 meeting.