A new study from the Cornell Center for Hospitality Research (CHR) found that tip percentages can indicate restaurant sales.

The study, “Tips Predict Restaurant Sales,” by professors Michael Lynn and Andrey D. Ukhov, analyzed seven years of monthly charge-card sales and tip data for a multiregional restaurant chain in the United States. Tip percentages in one month accurately predicted food sale levels in the following month, according to the report. The study concluded that these percentages can be used as a management device in restaurants to help set sales forecasts.