Though membership in the honor society Phi Beta Kappa is one of the nation’s oldest academic distinctions, the 62 Yale seniors and 10 juniors who were inducted into Phi Beta Kappa on Dec. 7 might not necessarily qualify at most other Ivy League universities.

The academic honors society has more than half a million members in 280 chapters at schools and universities across the country, and the requirements for students seeking admission vary widely, especially within the Ivy League. Criteria range from GPA to percentage of A grades; some schools also consider non-academic factors, such as character.

After being founded at the College of William and Mary in Virginia, the society spread to about 25 other universities. In 1883, the Chapter Constitution and Bylaws consolidated the chapters and established uniform rules and admissions criteria. The chapters created before the consolidation — including Yale, Harvard and Dartmouth — generally developed and retained their own distinct traditions, said Kate Soule, secretary and treasurer of Dartmouth’s Phi Beta Kappa and director of the college’s budget and financial affairs.

Soule said that although this allowed the universities to preserve their individuality, it also created disparities in the election criteria.

“It does mean that a student with the same GPA and course load would be inducted at one institution and not another,” she said.

Another cause of this variation is the fact that the national organization has few restrictions and standards for the way the individual chapters should run their elections, said Yale chapter president Haun Saussy, a professor of comparative literature.

“People always say, ‘Oh, well, what about fairness?’” Saussy said. “That’s always the trade-off.”

Dean of Undergraduate Education Joseph Gordon, who is also on the national governing board of Phi Beta Kappa, said in an e-mail that there are few restrictions because every university is different. Criteria vary with size and curriculum, he said.

For example, schools elect no more than 10 percent of their graduating class, so universities of different sizes must develop different systems to achieve the correct proportions. In addition, Gordon said, universities offer different types of degrees, such as liberal arts and pre-professional degrees, and so electors must consider a student’s educational program as well.

“There’s no perfect system, no single paradigm that fits all situations or produces an unquestionable result,” Gordon said. “But the PBK faculty at each school develops one that they feel best suits their student body and their curriculum, is practicable, and is equitable.”

At Yale, Phi Beta Kappa election is based mainly on the percentage of A grades earned, according to the chapter’s Web site.

“It has to do with how well people perform in a wide variety of courses,” Saussy said. “It’s not purely quantitative and not purely arbitrary.”

Similarly, Harvard’s system considers only academic factors but also controls for course difficulty and differences between majors, according to the chapter’s Web site. Undergraduate Phi Beta Kappa members serve as electors, separating applications into three groups based on area of concentration: social sciences, humanities and natural sciences. Each group is read by a separate committee, so applicants are judged only against those in the same discipline.

“What Harvard does is by hand,” Harvard chapter president and history professor Ann Blair said. “We are aware of the fact that not all courses are equal and not all grades are equal.”

Dartmouth, on the other hand, uses only GPA calculations to elect its members and has no board of electors at all. For the 2009-’10 academic year, students need only a minimum GPA of 3.82 and must not have a disciplinary record.

Soule said while Harvard’s system of election is laudable, it also requires significant time and effort.

“There was no movement among [Dartmouth] faculty to move away from only GPA,” she said.

There are many other minor differences among the chapters. For example, while Harvard, the University of Pennsylvania and Columbia University require tapped students to submit applications, including letters of recommendation, students at Yale, Dartmouth and Brown University do not send in supplementary materials.

Saussy said he thinks these disparities are not necessarily a negative thing.

“Uniformity is not really what we are seeking here,” he said. “Each school has its own traditions, its own style, priorities and emphases. It we want to force everyone into the same mold, it would not serve the purpose of the organization.”