Hospitals can easily tell you how much it will cost to leave your car in the parking lot. But how much it will cost for a simple test? That, a new study in JAMA Internal Medicine suggests, is much more difficult to track down.

Two researchers in Philadelphia reached out to 20 local hospitals, asking them how much they would charge for electrocardiogram. This is a pretty simple test to measure the rate of a heartbeat. It doesn't involve multiple doctors, nor is there any chance of a complication. And that was key to the study: The authors wanted to look at one of the most basic medical tests out there and see if hospitals could provide a price for it.

In the phone calls, the researchers would say they were uninsured and planning to pay for the test themselves, asking how much that would cost. Three hospitals were able to provide that information. By way of contrast, 19 hospitals were able to respond to a query about how much it would cost to park at the hospital, even when some of those parking prices had a few variables.

"The provision of parking prices would suggest that hospitals can indeed answer telephone queries about costs—when they want to," authors Jillian Bernstein and Joseph Bernstein write.

This study is a follow up to another one that the latter Bernstein worked on, where he and his co-authors called hospitals to ask how much a hip replacement would cost. Like in this study, they found that about 10 percent were able to provide a price. The idea here was to test out whether that had to do with the complexity of the procedure. A hip replacement's price could vary if, for example, there was an unexpected complication.

This new ECG study suggests that its really not about the complexity--that, overall, hospitals just aren't good at providing prices.

"Hospitals seem able to provide prices when they want to; yet for even basic medical services, prices remain opaque," Bernstein and Bernstein write. "Accordingly, medical insurance payment schemes that promote concern about prices without a commensurate increase in price transparency are apt to be ineffective."