Managing for Quality and Performance Excellence 10th Edition by James Evans ,William Lindsay

Exercise 30

Nearly everyone has eaten at McDonald's; the company sells millions of French fries each day. However, variation in the fries hasn't gone unnoticed. One Japanese news source challenged McDonald's Japanese weight standard with an experiment. Weighing 6500 grams of fries from 20 orders of large fries, it was concluded that the average order contained 10 grams less than the standard of 170 grams per large order. In New Zealand, multiple small-scale experiments were completed to determine value versus cost of upgrading order sizes. Averages of 12 fries and 13 grams were the only differences found between the medium and large orders, and for the price upgrade, it was concluded that it wasn't worth the cost.
To study variation in French fry lengths and cosmetic qualities, one student, Maggie Daly, measured 868 French fries, obtained from two small, medium, and large orders at two different McDonald's locations in Cincinnati, Ohio. Length measurements were recorded in centimeters. She also rated each fry on six cosmetic attributes: brown color or spots, broken or cracked, a piece of a whole fry, burnt potato skin on the fry, transparency (lack of crispness), and wilted texture. If a fry exhibited at least one of these, it was deemed nonconforming. The data are given in the Excel file French Fry Study.xlsx.
Use statistical tools discussed in this chapter to analyze the data. Consider the overall distribution of lengths, statistical summary of the data, percentage of conforming fries, and differences by location. You might also compute confidence intervals and conduct a hypothesis test to determine if differences exist by location.