Students from wealthier backgrounds have benefited the most from increases in financial aid from private universities in the past decade, according to a study released last week.

The study, released by Education Sector, an independent think tank, said that while 53 percent of students from the lowest income quartile and 35 percent of students from the highest quartile received financial aid from private schools in 1993, those proportions increased in 2000 to 56 percent and 51 percent, respectively. But critics said the report fails to take some key variables into account.

In addition to offering aid to more affluent students in the last decade, the aid packages granted to wealthy students were greater on average than those given to poor students in 2000 — averages of approximately $6,800 and $6,200 respectively. Students from either group received an average grant of approximately $5,500 in 1993, the report said.

Kevin Carey, the author of the report, said he thinks some universities no longer focus their use of financial aid to attract low-income students. He alleges that they prefer to “buy” the students with the highest SAT scores to boost their ranking, and that it is less costly to attract affluent students.

“If you’re more rational and exacting you can offer a wealthy student a small amount of financial aid and essentially attract them to your university over another,” he said. “It’s a financially rational decision, but has a socially detrimental outcome.”

But Robert Zemsky, founding director of the University of Pennsylvania’s Institute for Research on Higher Education, said he thinks the study fails to distinguish between financial aid and merit-based aid. He said he does not think the findings are a cause for alarm.

“The fundamental problem is that [Carey] confuses price discounting with financial aid so what he called merit aid is really price discounting,” Zemsky said. “I don’t think this is an issue of colleges are robbing from the poor and giving to the rich, which was the implication of the study.”

Carey said he is not opposed to merit scholarships, but he thinks that some universities use merit-based aid to attract wealthy students.

“Need-based aid is a system of ranking students by need, whereas what institutions call merit-based aid is not actually based on a system of merit,” he said. “It would be more accurate to call it non-need-based aid. There are legitimate merit-based scholarships and it’s fine to give students that motivation to do well academically.”

Still, Ohio University professor Richard Vedder, who is a member of the Education Department’s Commission on the Future of Higher Education, said the commission has discussed the data over the last couple weeks. He said he is concerned that universities are tilting their admissions policies to favor the wealthy.

“If you look at the top American universities and you look at the income composition of students attending those universities, they have been a little more tilted towards higher income kids over the last 20 years,” Vedder said.

Yale Dean of Undergraduate Admissions and Financial Aid Jeffrey Brenzel said that the study does not concern the University, since its admissions policy is need-blind.

Williams College professors Catharine Hill and Gordon Winston conducted a similar study in 2001, which found a shift towards need-based aid at the most elite and selective schools. Hill said the families of students in the lowest income quintile contribute much less than the 60 percent of annual income they did in the 1990s.

Hill also said she thinks universities should guarantee equal access to all students regardless of income.

“I would like to see schools really focus on guaranteeing access to students based on income,” she said. “I think if merit based financial aid is interfering with that, then that’s very unfortunate.”

Hill’s and Winston’s study focused on financial aid policies at the College of Further and Higher Education schools — a group of 33 private schools that include Yale, Williams, Amherst College and Cornell and Harvard universities.