Case Study

Service Enterprise IE-497B Dr. A.Ravindran October 5, 2007

Case Study #2 (Clean Sweep, Inc.)

Made by: Moises Eidelman
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Question #1) Plot the Run Charts for (a) total number of complaints and (b) complaints for each crew.

Part (a) Table 1 Total number of complaints per month month 1 2 3 4 5 6 7 8 9 # complaints 35 31 24 21 16 14 8 15 14

Figure 1 Run chart for total number of complaints 2

Part (b)

Table 2 Total number of monthly complaints per crew month 1 2 3 4 5 6 7 8 9 crew #1 7 5 3 3 4 2 1 4 3 Crew #2 8 8 6 6 4 6 4 3 5 Crew #3 11 11 12 8 5 5 2 6 5 Crew #4 9 7 3 4 3 1 1 2 1

Figure 2 Run chart for complaints for each crew

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Question #2) Prepare an X-bar chart for complaints and plot the average complaints for each crew during the 9-months period. Do the same for the performance ratings. Since there are 10 buildings, use n=10 as the sample size for the X-bar charts.

Table 3 Complaints per each building
Complaints about Cleaning Crews month 1 2 3 4 5 6 7 8 9 A 2 1 0 1 1 2 0 1 1 Be 5 6 6 5 3 5 4 2 2 Bw 7 8 8 4 2 3 2 4 4 C 3 2 1 1 2 0 1 2 1 D 2 1 0 0 0 1 0 1 1 E 3 1 2 1 1 0 0 0 0 F 2 2 2 1 1 0 0 1 1 G 4 3 4 4 3 2 0 2 1 H 3 2 0 1 1 1 0 1 3 I 4 5 1 3 2 0 1 1 0 X bar 3.5 3.1 2.4 2.1 1.6 1.4 0.8 1.5 1.4 Range 5 7 8 4 2 5 4 4 4

Table 4 Calculations and results for the UCL, CL and LCL of complaints

X double bar = 1.9778 R bar = 4.7778 A2 = 0.3080 UCL = 3.4493 CL = 1.9778 LCL = 0.5062

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Figure 3 X-bar chart for average # of complaints per crew

Table 5 Performance rating per building
Performance Ratings about Cleaning Crews month 1 2 3 4 5 6 7 8 9 A 7 7 8 7 6 7 8 6 7 Be 5 5 5 5 6 6 7 6 7 Bw 3 3 4 5 6 6 7 5 5 C 6 6 6 8 7 7 6 7 6 D 7 6 8 8 8 7 6 7 7 E 5 5 5 6