Here are the A, B, Cs of why Minneapolis inspectors don't grade restaurants

Above: An 'A' scoring restaurant in New York City (Flikr photo by user mtchlra)

Should Minneapolis be grading its restaurants?

Several commenters on our story Tuesday about food inspections suggested the city join other areas -- such as New York, San Diego, Los Angeles and most recently Boston -- in requiring restaurants to post food safety letter-grades in their windows.

Minnesota is actually one of the least transparent states in the nation with regard to restaurant inspections. Hawaii is the only other state where no local jurisdictions post inspection information online, according to a roundup by Food Safety News.

A local developer posted Minneapolis restaurant inspections to the Web several years ago, but ultimately took the site down after trouble getting up-to-date data from the city. The city's health department said it hopes to have this data live in 2016, though it had similar goals in 2013.

With regard to letter grades in particular, the city's Environmental Health Manager Dan Huff is not a fan.

"What we have found is that jurisdictions that do have grades, more resources go into fighting over the grade than actually improving food safety," Huff said.

He believes it would be detrimental to the inspection process. "It creates a more adversarial relationship with the inspector," Huff said. "Because you're like 'Come on! I just need one point so I'm an A. Give me a break man.'"

Above: A grade label in Los Angeles (via Flickr user ericejohnson).

Council Member Andrew Johnson, meanwhile, has asked staff to explore the idea further.

"Making it so people can go out to the website and look up restaurants is … a great step," Johnson said. "But it also would be even better to have higher visibility that incentivizes businesses to put safety first and health first."

Professor Craig Hedberg, a foodborne illness expert at the University of Minnesota, said there has not been much research into the effectiveness of various grading systems.

The methodology can vary widely. It's much easier to get an 'A' in Los Angeles, for example, than it is in New York City, Hedberg said. Analysis of New York's system found that many 'A' restaurants had racked up nearly enough violations to fall to the next grade -- raising questions about how specific to make the grading.

Above: NYC inspection records from 2010-2011. Blue represents 'A' grades, green represents 'B' grades. From The New York Times.

There is an indication the grades can make a difference. Academic research of Los Angeles' program, adopted in 1998, found it to be associated with a 13.1 percent drop in foodborne-illness hospitalizations.

Another analysis in 2012, however, found little evidence that grading systems were effective in reducing foodborne illness.

Hedberg said one of his students is now looking at salmonella data from jurisdictions that require on-site postings of some inspection information. The very preliminary finding has been that letter grades coincide with a drop in salmonella rates.

"And when we look at jurisdictions that have some posting other than letter grades, we don't see a change," Hedberg said. "Suggesting that there's something about the letter grade that actually changes the whole dynamic around the posting of the inspection result."

The relationship between restaurants and inspectors also matters, however. In 2002, Minneapolis began combining unannounced inspections with inspections that are pre-scheduled and geared toward education -- a practice that is no longer used.

A 2007 study by University of Minnesota researchers, including Hedberg, found that the pre-scheduled inspection significantly reduced the number of key critical violations found during a subsequent unannounced inspection. Restaurants with the pre-scheduled inspections were also more likely to report foodborne illness incidents to the city's health department.

That matters because of how customers report illness. "We know that when people think they experience illness from a restaurant, they're [about] 3 times as likely to call the restaurant as they are to call the Health Department," Hedberg said.

Not all cities are convinced by letter grades. Baltimore ditched a proposal last year to adopt them, over concerns that it would negatively impact restaurants.