# Need help calculating control limits for x-mr control chart

August 30, 2017

Question
Need help calculating control limits for x-mr control chart

Deliverable: XmR Chart
Student last name:
Upper control limit for the range::: 48.9800 (unsure)
Upper control limit for the individuals::: 64.9300 (unsure)
Lower control limit for the individuals::: 0.0000 (unsure)
What would you recommend? Continuing using a control chart to ensure quality
Is the measurement system discriminate? Yes
What is causing the point to be assignable cause variation
out of control?

Objective: Earlier, you have made some progress as a result of the stem-and-leaf diagram. How did the team make the improvement? They saw that the diagram showed a bi-modal condition so the team identified the source of this condition; eliminated one of the sources and optimized accordingly. The two sources were found to be: 1) Some of the patients were first-time visitors and 2) Some of the patients were return visitors. The team changed the process so that first-time visitors were processed ahead of time, thus reducing their time waiting in the waiting room. This dramatically decreased the overall average wait time. But, the team learned more through the use of designed experiments. There were other improvements made through the use of other Six Sigma tools and techniques (aside from your project deliverables) and now the wait times are acceptable. Now, you want to ensure that they are staying that way and you want to practice “prevention” versus “detection.” Part of your CONTROL strategy is to employ the use of an on-going capability study to ensure ‘the plates are still spinning’–so-to-speak. And, the next deliverable will do that, but prior to performing a capability study, one must make sure the process is in statistical control. This is good, because the team decided to use a control chart as part of the CONTROL phase anyhow, so this will work out fine. In fact, let’s do one nowâ€¦just to make sure we are in statistical control. Instructions for you: Answer the questions and type those responses in the peach-colored box below.

1 10
2 17
3 29
4 39
5 55
6 64
7 28
8 6
9 5
10 3
11 39
12 46
13 35
14 30
15 6
16 32
17 33
18 11
19 20
20 13
21 9
22 14
23 12
24 30
25 56
26 62
27 73
28 54
29 10
30
9

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