Asked by Jennifer Feliz on May 20, 2024
Verified
A city police chief decides to do an annual review of the police department by checking the number of monthly complaints. If the total number of complaints in each of the 12 months were 15, 18, 13, 12, 16, 20, 5, 10, 9, 11, 8, and 3 and the police chief wants a 90% confidence level, are the complaints in control?
Confidence Level
A statistical measure that quantifies the probability of a parameter lying within a specified range of values, often used in the context of confidence intervals.
Control
In management, it refers to the process of monitoring activities to ensure they are being accomplished as planned and correcting any significant deviations.
- Investigate sample data to judge whether a process complies with statistical standards.
- Identify the differences between normal process fluctuations and variations resulting from assignable causes.
Verified Answer
JH
Jessica HuynhMay 20, 2024
Final Answer :
From Table S6.2 in the text, z = 1.65
c-bar = (15 + 18 + 13 + 12 + 16 + 20 + 5 + 10 + 9 + 11 + 8 + 3)/12 = 11.67 complaints
UCL = 11.67 + 1.65 (v 11.67) = 17.307 complaints
LCL = 11.67 - 1.65 (v11.67) = 6.033 complaints
Since the points 18 and 20 fall above the UCL and points 5 and 3 fall below the LCL, the complaints are not in control.
c-bar = (15 + 18 + 13 + 12 + 16 + 20 + 5 + 10 + 9 + 11 + 8 + 3)/12 = 11.67 complaints
UCL = 11.67 + 1.65 (v 11.67) = 17.307 complaints
LCL = 11.67 - 1.65 (v11.67) = 6.033 complaints
Since the points 18 and 20 fall above the UCL and points 5 and 3 fall below the LCL, the complaints are not in control.
Learning Objectives
- Investigate sample data to judge whether a process complies with statistical standards.
- Identify the differences between normal process fluctuations and variations resulting from assignable causes.
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