When shopping classes, Yale students usually rely on word of mouth to find out what kind of grades a professor gives.

But now a student-run Web site launched this shopping period, Gradifi.com, promises to provide a more statistically sound method of determining the impact certain classes have on grade-point averages, based on students’ previous grades in other classes and the grades received by students of similar academic profiles.

Gradifi.com is the brainchild of Dan Loewenherz ’09, who said he wanted to give Yale students more information as they pick classes — namely, grades. The response to Gradifi among Yale students and professors has been mixed, with some saying they think it would be valuable to see the grade distribution and others citing concerns that students would not provide accurate information. In response to Gradifi, University administrators said students are already given enough information to choose courses without needing to know grades.

Loewenherz said he first thought up the idea for Gradifi in response to what he viewed as the inadequacies of the Online Course Information Web site.

“I looked at OCI and said, ‘There’s something wrong here,’” Loewenherz said. “We have all this information, sure, but most of it we could get from friends. The course comments range from saying ‘this is the best course’ to ‘don’t even take this course.’ And you don’t get the grades for the course, either.”

Gradifi uses a complex algorithm to determine the grades students would likely get from a course based on the grades they entered for courses already taken. The site will eventually feature a page for each course, Loewenherz said, complete with grade-distribution graphs, reviews for every professor who taught the course and the ability to compare workloads for different courses and professors.

Loewenherz emphasized that everything on Gradifi is strictly confidential and anonymous.

By Loewenherz’s estimation, Gradifi will reach an acceptable standard of accuracy once it has about 5,000 class reviews, and about 1,000 student users. As of 7:36 p.m. Tuesday, Gradifi had 114 users and 330 class reviews. But Loewenherz said he expects the site to be fully functional by the end of the week.

An informal poll of 25 Yale students conducted by the News revealed a variety of reactions to Gradifi. All but three students said information provided on OCI was adequate for choosing courses. Half the students said seeing a course’s grade distribution would be helpful in selecting classes.

“In one way, students could take it easy, just taking courses they know they’d get good grades in,” Frank Teng ’12 said. “Or they could really challenge themselves.”

Added Mikie Mekeel ’11:“If I knew that 40 percent of people got A’s in a class, and 10 percent got A minuses, I’d be more willing to take that course than one where 10 percent got A’s and 40 percent got A minuses.”

Many students said Gradifi could be “dangerous,” tempting students to take courses based solely on grades. One student, who spoke on the condition of anonymity, said Gradifi could lead teachers to change their grading.

“If the grade distribution for a ‘gut’ gets out there, then the teacher will change their grading from giving mostly A’s to mostly C’s,” the student said.

Professors were also split on the idea of a Web site like Gradifi.

“It does seem to me that the information about grade distribution would be of interest to students considering [courses outside their area of expertise],” English professor Leslie Brisman said. “It would hold little interest for students of the humanities in choosing humanities courses or science students in considering science courses.”

But psychology professor Margaret Clark questioned the validity of the data provided.

“You have to ask whether [students] would report the grade distributions accurately,” she said.

Dean of Undergraduate Education Joseph Gordon said in e-mail that similar commercial sites providing academic information already exist, but they are flawed in that the information gathered by such sites is not independently verified.

Gradifi cannot verify that students are providing legitimate information regarding grades or courses, but Loewenherz said he is not concerned about students’ providing false data.

“You wouldn’t want to sabotage the system,” Loewenherz said.

And, Gordon said, Yale already provides plenty of information to students in the form of freshman counselors, advising fairs, residential-college deans and the OCS Web site.

“Distribution of grading in a course is not good basis of informing a choice of whether or not to enroll in that course,” Gordon wrote.