Data met discourse Tuesday when Philadelphia City Commissioner Stephanie Singer, along with representatives of racial and ethnic organizations, religious leaders, and researchers, gathered to trumpet the results of a recent study on Pennsylvania's new voter-ID law and denounce its requirements.

"Today's news conference really is to dramatically show you . . . the impact of voter-ID law," J. Whyatt Mondesire, president of the Philadelphia chapter of the NAACP, said at Bright Hope Baptist Church in North Philadelphia.

Researcher Tamara Manik-Perlman conducted a geographic analysis of voter data from Singer's office, Pennsylvania's Department of State, and the 2010 census. Manik-Perlman, who works at the Philadelphia-based geographic data analysis firm Azavea, conducted the analysis free over a day and a half.

She reported a strong statistical relationship between certain racial groups and the percentage of the population without valid driver's licenses or other state Department of Transportation ID that would qualify under the new law.

Examining wards by racial population, there was a strong relationship between high white population percentages and a low percentage without valid PennDot ID, and between a high black population percentage and a high percentage without valid PennDot ID. A moderate positive relationship was found between a neighborhood's Latino percentage and its percentage of invalid PennDot ID.

Those findings were based on information released by the Department of State, which includes the names of many people who have PennDot identification but appeared on the state's list anyway.

The relationship was strongest for those with expired ID - the new law does not allow ID that has been expired for more than a year from the election date - and weak for those with no PennDot ID. Higher populations of black voters tended to correlate with higher percentages of expired IDs; the opposite effect was true for white voters.

A challenge to the state law by the American Civil Liberties Union, the NAACP, and others is being considered by Commonwealth Court Judge Robert E. Simpson Jr., who is expected to rule within the next few weeks. Separately, the U.S. Department of Justice is reviewing data from the state to determine whether the law complies with the Voting Rights Act.

Singer, a Democrat and chair of the three-member Board of City Commissioners, said her interest went beyond race and legality.

"There's the legal question," Singer said, "but then there's also the moral, political question of 'How many people does this affect?' The goal here is free and fair elections."

Al Schmidt, the board's lone Republican member, declined to comment on the news conference because he did not attend.