Examine the first FRED graph. In order to accurately compare the dollar value of retail sales of food and beverages across time the data must be Examine the first FRED graph. In order to accurately compare the dollar value of retail sales of food and beverages across time the data must be adjusted for the impact consumer-price inflation. transformed into an index with a value of 100 for the base date. transformed into a year-to-year percent growth rate. adjusted for the impact of economic recessions