In an attempt to improve efficiency, Starbucks has implemented "lean" Japanese techniques at many of its 11,000 U.S. stores (The Wall Street Journal, August 4, 2009). By reducing the time baristas (employees) spend on bending, reaching, and walking, they will have more time to interact with customers and improve the Starbucks experience. Suppose Starbucks adopts the lean technique at Store 1, but makes no changes at Stores 2 and 3. On a recent Monday morning between the hours of 7:00 am and 8:00 am, the following statistics were obtained relating to average time per order (in seconds):

Store 1: x1 = 56, n1 = 18

Store 2: x2 = 66, n2 = 12

Store 3: x3 = 63, n3 = 14

Excel produced the following ANOVA table:

a. Compute 95% confidence interval estimates for all paired differences for the means using Fisher's LSD approach.
b. Repeat the analysis with Tukey's HSD approach.
c. Which of these two approaches is more reliable? Explain.
d. Do the data suggest that the lean technique is improving efficiency? Explain.

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Source of Variation Between 811.70 2 405.85 52.115.5E-12 3.226 Groups Within 319.30 41 7.79 Groups df MS F p-value F crit Total 1131.0043