Some college students spend their summers working as lifeguards or interns. Jaime Rosenthal spent hers calling 102 hospitals across the country to find out how much a hip replacement would cost.

Rosenthal, now a senior at Washington University in St. Louis, was working on a research project at the University of Iowa about health-cost transparency. How easy, they wanted to know, would it be to find out the price for one of the most common surgical procedures?

Not very: Only 10 percent of the 102 hospitals contacted (two in every state and the District of Columbia) were able to give Rosenthal a complete price for the procedure, as she and her co-authors write in this week's JAMA Internal Medicine. Even more, once they did track down the prices, they were all over the map, ranging from $11,000 to $125,000.

"It was definitely frustrating," Rosenthal says. "I learned a lot about the health care system and the need for pricing transparency, which I never really considered."

While three researchers were working on the project, it was Rosenthal who called up over 100 hospitals inquiring about the price of a hip replacement for her 62-year-old, uninsured grandmother (who was a fictitious character.)

The call followed a set script: Rosenthal would call the main line at the hospital, explain her query and ask to be transferred to whoever could help. Each hospital was contacted up to five times to obtain pricing information.

"They would usually transfer me," she says. "A lot of times they didn't know who could answer it ,and I would get transferred between offices. It was really time consuming. A lot of them just sent me to billing, since that seemed like it was money related."

Rosenthal also contacted the 20 top-ranked hospitals across the country, according to US News and World Report. She found that nine of those hospitals could give her a complete price for the procedure, and three more could provide the information when she contacted both the doctor and the hospital.

Among the randomly-selected hospitals, the data was scarce: 10 could provide a price for the procedure, although there were 54 who could do so when she contacted both the hospital and doctor separately.

The prices that Rosenthal did obtain varied hugely, as you can see in this chart below. Row A represents the top-ranked hospitals; Row B shows those that were selected at random.

"Among both top-ranked and non-top-ranked hospitals, total price estimates ranged from $10,000 to well over $100,000," Rosenthal and her co-authors write. "For reference, available data suggest that Medicare and other large payers frequently pay between $10,000 and $25,000 for primary joint replacement surgery."

Rosenthal thinks she probably had an easier time soliciting cost estimates from the hospitals than the average consumer. She knew the exact medical codes that represented the procedure she was asking about; most of us would have no clue about that.

"If you didn't have those, I think it would be a lot harder," she says.

Rosenthal's findings are not exactly an anomaly in medical research: A study published in the Archives of Internal Medicine in the spring found even greater variation in prices for an appendectomy. Depending on where it was performed, the very simple procedure could cost anywhere from as little as $1,529 to as much as $182,955.