One of the most frustrating experiences for consumers is choosing a doctor for surgery.

Now a nonprofit consumers group has come out with a free surgeon rating tool that allows consumers to type in a Zip code and search for the top-performing surgeons in 14 types of major surgery. They include: heart valve and bypass surgery, total knee and hip replacement, gastric (stomach), hernia, and spine fusion surgery.

The ratings are based on an analysis of federal government records of more than 4 million surgeries performed by more than 50,000 doctors. Using star ratings (5 stars being the best), the group identified surgeons who have better-than-average performances based on three criteria:

• Death rates

• Other bad outcomes, such as infections, falls or other complications that resulted in longer hospital stays or re-admissions.

• Recommendations by other doctors

The Web site, www.surgeonratings.org, was created by Consumers' Checkbook/Center for the Study of Services, a nonprofit that publishes many consumer guides, including one rating top doctor specialists in more than 50 metropolitan regions and another rating more than 4,500 U.S. acute-care hospitals. The group gathered the information from Medicare claims data used to pay doctors and hospitals from 2009 to 2012.

But not every surgeon is listed. The ratings don't include poor performers. That might come later.

"This is the first time we're doing this and it's going to catch people by surprise," said Robert Krughoff, Checkbook's president. "So we chose this time to focus on the good ones. and to tell people who they are."

The site allows consumers to select a type of surgery, type in a Zip code, and search for the top performing physicians as far away as 500 miles. Once the physicians are listed, consumers can also select which ones they want to compare. The site will also show the doctors' board certification, education and training.

The site also provides information about the performance of the hospital where the surgeries are done.

Some surgeons aren't listed because the consumers group only included doctors who had performed enough surgeries to provide statistically meaningful comparisons. In other words, researchers wanted to make sure the good track record wasn't the result of luck alone. A surgeon who gets a 5-star rating, for example, means the nonprofit is 97.5 percent sure that the surgeon's performance is better than the average U.S. surgeon.

For the new site, surgeons' results are adjusted to take into account how frail or sick their patients were. Even after this adjustment, however, results varied dramatically from surgeon to surgeon. For heart valve and heart bypass surgery, the patients of the best-peforming one-tenth of surgeons had death rates of less than 3 percent in the hospital or within 90 days of discharge, compared to death rates of more than 11 percent for patients of the worst-performing one-tenth of surgeons.