 Two Stanford University economics researchers found that higher lettered restaurants scored a rise in revenue, while lower lettered restaurants have seen their revenues decline.The quality of restaurants in the entire county became more acceptable, with the average score going up from about 75% to nearly 90% in the year after restaurant grading was implemented.The researchers concluded that the results were not explained solely by consumers switching to higher quality restaurants, and that some of the effect had to do with restaurants making changes due to grade cards.