Philanthropy consulting firm Arabella Advisors has acquired a San Francisco-based analytics company to help it meet growing demand from foundations for quantitative evidence to assess the social impact of their programs.

Arabella has more than 20 clients in the Washington region — primarily foundations and individual philanthropists. In acquiring Blueprint Research + Design, Arabella said it will have greater capacity to analyze statistics, surveys and other data to measure social change and industry trends.

Eric Kessler, founder of Chicago-based Arabella Advisors, said Blueprint can give philanthropists financing such projects as school reform in the District a much clearer picture of whether their money is being put to good use.

“Before, we would interview people and get stories about the impact they’re having,” he said. “Now we can actually do the data analysis.”

Kessler said the acquisition is a step forward in “making sure that every penny [from philanthropists] is making an impact.”

Arabella, which has 60 employees after the acquisition, would not disclose names of its current clients. It previously worked with the Annie E. Casey Foundation’s disaster relief efforts and Bill and Melinda Gates Foundation education reform initiative that administered projects in the District. Blueprint designed strategies for programs including the John D. and Catherine T. MacArthur Foundation’s youth and digital media project.

Motley Fool’s philanthropic arm, Foolanthropy, consulted Arabella to reshape its grant-giving program. While they give regularly to the Carpenter’s Shelter and Thurgood Marshall Academy, Foolanthropy officials say they rely heavily on data “to easily see and experience the impact our charitable efforts are having in our community,” said Maryam Zaidi, Foolanthropy account executive.

Some experts say that because of the economic downturn, businesses and foundations no longer blindly write checks to nonprofits but instead want evidence that they are getting a return on their investment.

“The recession has been a driver for donors and philanthropists who were already concerned about impact to be even more concerned, as they have fewer dollars to invest,” said Tamara Copeland, president of the Washington Regional Association of Grantmakers. “When I talk to foundations and corporate giving programs . . . I hear them having very clearly defined objectives.”

The two companies have begun integration.

“The deal is bringing together the very focused, high-boutique consulting services that Blueprint was doing for the big guys and providing those services to all levels,” said Blueprint founder and president Lucy Bernholz.