QSR has been reporting on the largest quick-serve and fast-casual brands in the United States for nearly 15 years. The file QSR contains the food segment (burger, chicken, pizza, or sandwich) and U.S. average sales per unit ($thou-sands) for each of 58 quick-service brands. (Data extracted from bit.ly/Oj6EcY.)
a. At the 0.05 level of significance, is there evidence of a difference in the mean U.S. average sales per unit ($ thousands) among the food segments?
b. At the 0.05 level of significance, is there a difference in the variation in U.S. average sales per unit ($thousands) among the food segments?
c. What effect does your result in (b) have on the validity of the results in (a)?