Dr. Patel is concerned about the long wait times in his office. The following table presents six
Question:
- Dr. Patel is concerned about the long wait times in his office. The following table presents six random observations for the patient waiting times over a period of 12 days.
Observations (mins) | ||||||
Day | 1 | 2 | 3 | 4 | 5 | 6 |
1 | 21 | 27 | 32 | 25 | 30 | 29 |
2 | 22 | 33 | 30 | 31 | 27 | 34 |
3 | 20 | 29 | 26 | 24 | 32 | 30 |
4 | 32 | 32 | 21 | 34 | 28 | 29 |
5 | 34 | 26 | 35 | 27 | 30 | 26 |
6 | 35 | 30 | 29 | 30 | 31 | 27 |
7 | 38 | 36 | 42 | 35 | 40 | 32 |
8 | 35 | 29 | 30 | 25 | 28 | 30 |
9 | 22 | 25 | 26 | 30 | 36 | 28 |
10 | 26 | 26 | 34 | 34 | 25 | 36 |
11 | 29 | 26 | 20 | 31 | 32 | 33 |
12 | 28 | 22 | /24 | 27 | 32 | 31 |
- Dr. Patel is willing to use three-sigma limits. Use the given data and the factors from Table 3.1 (page 110) to construct R-chart and xx-chart.
- Interpret your charts. Are the process mean and process variability in statistical control?
- The patient surveys indicate that they are willing to wait between 10 and 30 minutes before seeing Dr. Patel. Calculate the process capability index and capability ratio at the three-sigma level. Is the process capable of meeting this demand at the three-sigma level?
Table pg 110
Size of Sample Factor for UCL & LCL Factor for LCL Factor for UCL
(n) For X-chart (A2) For R-Chart (D3) For-Chart (D4)
2 1.880 0 3.267
3 1.023 0 2.575
4 0.729 0 2.282
5 0.577 0 2.115
6 0.483 0 2.004
7 0.419 0.076 1.924
8 0.373 0.136 1.864
9 0.337 0.184 1.816
10 0.308 0.223 1.777
- x-bar Chart: https://www.youtube.com/watch?v=RiKUZqW41UM
- R-Chart: https://www.youtube.com/watch?v=0CtJJGprG6A
- Process Capability Ratio: https://www.youtube.com/watch?v=WHpW5lVbuqU
- Process Capability Index: https://www.youtube.com/watch?v=wPRd2RgoC0E
Business Statistics a decision making approach
ISBN: 978-0133021844
9th edition
Authors: David F. Groebner, Patrick W. Shannon, Phillip C. Fry