When customers visit Amazon.com, the Web site lets them sample parts of books for free. Some open-education advocates think this try-it-before-you-buy-it idea offers an answer to one of the biggest questions facing the movement to publish course materials free online: What business model can support giving away your content?

New research takes a close look at what happened when one institution, Brigham Young University, experimented with granting free access to the content of some of its distance-education courses. The study examined the cost of opening up those materials and the impact their publication had on paid enrollments, a concern for institutions worried that giving away free courses could cannibalize their ranks of paying students.

The data suggest they needn’t worry. Opening the courses “provided neither a large positive marketing effect that boosted enrollments nor a large negative free-rider impact decreasing enrollments,” wrote Justin K. Johansen, who conducted the study as a dissertation in instructional psychology and technology at Brigham Young, where he also serves as director of independent study.

“Really, the OpenCourseWare ended up serving as an advertising tool,” Mr. Johansen said in an interview. Over all, the six opened courses attracted 13,795 visits and 445 paid enrollments in four months. But Mr. Johansen cautions that the limited length of the pilot study meant that a “statistically significant” measure of the impact of opening the classes on paid enrollment “was not possible.”

When it came to cost, the study found the primary expense was developing the software tools to convert courses from their existing format to one appropriate for open publication. The first university course took $3,485 to open, but the average cost for subsequent college-level courses dropped to $284.

David Wiley, a Brigham Young associate professor and open-education leader, praises Mr. Johansen's research as "the first piece of empirical work I am aware of that demonstrates clearly that a distance-learning program can simultaneously (1) provide a significant public good by publishing open courseware and (2) be revenue positive while doing it."

That could be welcome news for a movement whose past projects have been largely paid for by outside grants. The philanthropic support is now running out for key ventures, a situation that has already shut down Utah State University's OpenCourseWare. Writes Mr. Johansen: "From a financial perspective, there do not appear to be any organizations currently running large-scale, self-sustaining open-publishing initiatives."