Pittsburgh officials and community development groups today revealed the findings of a five-month study of the city's residential market that will be used to guide investment in housing.

Officials pitched it as a way to make decisions based on a mix of hard data and neighborhood input, rather than on politics.

"In years past, somebody would get an idea or a whim and say, 'You know what? We've got to build five houses on that street,' " said Kendall Pelling, a project manager at East Liberty Development Inc. Politics then determined whether that happened. "There wasn't a data-driven piece to that."

That gap prompted the city to bring in The Reinvestment Fund, a Philadelphia-based nonprofit group that has studied Philadelphia and Baltimore. The organization's final product is an interactive map, which will be put online within weeks, that shows the relative strength of housing markets throughout the city.

It incorporates data on the number of homes and businesses, sale prices, vacancies, new houses, building code violations, foreclosures, and the prevalence of Section 8 subsidized housing. The composite map applies a seven-shade color scale to city areas, with stable or improving housing markets in purple and blue, and weaker ones in shades of orange and yellow.

It finds the strongest markets in Squirrel Hill and Shadyside, Highland Park and parts of Banksville and Brookline. The weakest markets are in parts of Homewood, Lincoln-Lemington, Perry South, Beltzhoover and Hazelwood.

Rob Stephany, interim executive director of the Urban Redevelopment Authority, said that the key is not "what the color of the neighborhood is" but what the underlying data says and where an area fits into the entire city's market. For instance, Homewood is distressed, but the strength of nearby Point Breeze suggests that investments along the border might spur activity that could then spread deeper into Homewood.

The study will also be used to guide an effort to create a development master plan for the city, said city Planning Director Noor Ismail. "It allows us to look at the city as a whole at the same time that neighborhood groups are looking at their specific pieces," she said.

Even as the data was being gathered, city officials were using it to help shape neighborhood decisions. For instance, the Brightwood Civic Group, which serves the Marshall-Shadeland neighborhood, was considering building 17 new houses, which might have entailed $2.2 million in public aid and five years of work. The data led the group to scale back its plans to three houses, plus green space that will enhance the value of existing homes. That frees up public dollars to fight decline at sites throughout the neighborhood, said Ed Brandt, who directs the group.

City Neighborhood Initiatives Director Kim Graziani said that Mayor Luke Ravenstahl's administration will set up a series of community meetings on the study and its implications from late May through July, while trying to round up more funding for investment driven by the data.

The study cost $35,000 and was paid for by the URA and the Surdna Foundation.