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Questions and Answers
What should be done when a sample is deleted from a data set in the templates?
What should be done when a sample is deleted from a data set in the templates?
What is the purpose of rescaling the vertical axis of the charts?
What is the purpose of rescaling the vertical axis of the charts?
What is the common characteristic of the out-of-control samples in the x-bar chart?
What is the common characteristic of the out-of-control samples in the x-bar chart?
What should be done with the out-of-control samples in the x-bar and R-charts?
What should be done with the out-of-control samples in the x-bar and R-charts?
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What is the purpose of updating the number of samples used in the calculations when deleting sample data?
What is the purpose of updating the number of samples used in the calculations when deleting sample data?
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What is the purpose of the new production data and revised control charts shown in the image?
What is the purpose of the new production data and revised control charts shown in the image?
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What is the purpose of constructing x-bar and R-Charts in process monitoring and control?
What is the purpose of constructing x-bar and R-Charts in process monitoring and control?
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Why is estimating process capability using control chart data less accurate than using the complete set of data?
Why is estimating process capability using control chart data less accurate than using the complete set of data?
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What should workers do after a process is determined to be in control?
What should workers do after a process is determined to be in control?
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Why do workers need to be trained to use control charts properly in process monitoring?
Why do workers need to be trained to use control charts properly in process monitoring?
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How are the overall mean and average range used in process capability index calculations?
How are the overall mean and average range used in process capability index calculations?
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What is one limitation of using x-bar and R-Charts for estimating process capability?
What is one limitation of using x-bar and R-Charts for estimating process capability?
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What modification should be made to the formula in cell C9?
What modification should be made to the formula in cell C9?
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What should the formula in cell C10 be changed to?
What should the formula in cell C10 be changed to?
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What is the reason for modifying the formulas in cells C9 and C10?
What is the reason for modifying the formulas in cells C9 and C10?
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What does changing the number of samples in cell E6 affect?
What does changing the number of samples in cell E6 affect?
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Why should the formulas in cells C9 and C10 use only the column range of the original data?
Why should the formulas in cells C9 and C10 use only the column range of the original data?
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How does modifying the formulas in cells C9 and C10 affect the charting of data?
How does modifying the formulas in cells C9 and C10 affect the charting of data?
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What does the new ISO standard 11462-1 provide guidance for?
What does the new ISO standard 11462-1 provide guidance for?
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What sample size is effective for detecting process shifts of two standard deviations or larger?
What sample size is effective for detecting process shifts of two standard deviations or larger?
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What does the ISO standard 11462-1 address regarding SPC systems?
What does the ISO standard 11462-1 address regarding SPC systems?
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In order to detect smaller shifts in the process mean, what range of sample size must be used?
In order to detect smaller shifts in the process mean, what range of sample size must be used?
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Where should the control limits be located according to the text?
Where should the control limits be located according to the text?
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What aspect does the standard 11462-1 NOT provide guidance on?
What aspect does the standard 11462-1 NOT provide guidance on?
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What is the purpose of a u-chart?
What is the purpose of a u-chart?
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What assumption is made when using a u-chart?
What assumption is made when using a u-chart?
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Which statistic is used to compute the control limits for a u-chart?
Which statistic is used to compute the control limits for a u-chart?
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What is the first step in constructing a u-chart?
What is the first step in constructing a u-chart?
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What is the formula used to calculate the control limits for a u-chart?
What is the formula used to calculate the control limits for a u-chart?
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In the spreadsheet template example shown, what is the value of the lower control limit (LCL)?
In the spreadsheet template example shown, what is the value of the lower control limit (LCL)?
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Control limits for x-bar and R-charts are the same as those for u-charts.
Control limits for x-bar and R-charts are the same as those for u-charts.
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Increasing variation in a process will lead to wider control limits in an x-bar chart.
Increasing variation in a process will lead to wider control limits in an x-bar chart.
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The ISO standard 11462-1 provides guidance on constructing individual charts.
The ISO standard 11462-1 provides guidance on constructing individual charts.
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Low volume operations are best monitored using x-charts.
Low volume operations are best monitored using x-charts.
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An upward trend in the average values on an x-bar chart indicates a process improvement.
An upward trend in the average values on an x-bar chart indicates a process improvement.
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Control limits for moving range-chart are calculated based on the average moving range.
Control limits for moving range-chart are calculated based on the average moving range.
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To estimate process capability using x-bar and R-charts, one should collect between 25 and 30 samples, with sample sizes generally between 3 and 10.
To estimate process capability using x-bar and R-charts, one should collect between 25 and 30 samples, with sample sizes generally between 3 and 10.
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The estimate of the standard deviation using control chart data is as accurate as calculating the standard deviation using the complete set of data.
The estimate of the standard deviation using control chart data is as accurate as calculating the standard deviation using the complete set of data.
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The overall mean and average range are used in process capability index calculations.
The overall mean and average range are used in process capability index calculations.
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To detect smaller shifts in the process mean, sample sizes between 3 and 10 should be used.
To detect smaller shifts in the process mean, sample sizes between 3 and 10 should be used.
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After a process is determined to be in control, workers should continue using control charts to monitor performance and identify any special causes.
After a process is determined to be in control, workers should continue using control charts to monitor performance and identify any special causes.
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The formula used to calculate control limits for a u-chart is provided in the text.
The formula used to calculate control limits for a u-chart is provided in the text.
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The formula in cell C10 should be changed to calculate the upper control limit (UCL) for the u-chart.
The formula in cell C10 should be changed to calculate the upper control limit (UCL) for the u-chart.
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Updating the number of samples used in the calculations when deleting sample data is not necessary, as it does not affect the charting of the data.
Updating the number of samples used in the calculations when deleting sample data is not necessary, as it does not affect the charting of the data.
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The ISO standard 11462-1 provides guidance on the aspect of defining the appropriate sample size for detecting process shifts of two standard deviations or larger.
The ISO standard 11462-1 provides guidance on the aspect of defining the appropriate sample size for detecting process shifts of two standard deviations or larger.
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When a process is determined to be in control, workers should immediately start making changes to the process to improve its performance.
When a process is determined to be in control, workers should immediately start making changes to the process to improve its performance.
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The purpose of a u-chart is to monitor the number of nonconforming units in a sample, while an x-bar and R-chart is used to monitor the fraction of nonconforming units.
The purpose of a u-chart is to monitor the number of nonconforming units in a sample, while an x-bar and R-chart is used to monitor the fraction of nonconforming units.
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The ISO standard 11462-1 provides guidance on the aspect of constructing and interpreting control charts for process monitoring and control.
The ISO standard 11462-1 provides guidance on the aspect of constructing and interpreting control charts for process monitoring and control.
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The formula in cell C9 should be changed to: =SUMIF(B13:AE13, ">-99999", B23:AE23)/$E$6.
The formula in cell C9 should be changed to: =SUMIF(B13:AE13, ">-99999", B23:AE23)/$E$6.
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To maintain the established control limits, the number of samples in cell E6 should be increased when modifying the formulas in cells C9 and C10.
To maintain the established control limits, the number of samples in cell E6 should be increased when modifying the formulas in cells C9 and C10.
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Changing the formulas in cells C9 and C10 for the calculations of the grand average and average range will affect the established control limits.
Changing the formulas in cells C9 and C10 for the calculations of the grand average and average range will affect the established control limits.
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The template will no longer chart all the data once the modifications are made to cells C9 and C10.
The template will no longer chart all the data once the modifications are made to cells C9 and C10.
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The modified formula in cell C10 should read: =SUMIF(B13:AE13, ">99999", B28:AE28)/$E$6.
The modified formula in cell C10 should read: =SUMIF(B13:AE13, ">99999", B28:AE28)/$E$6.
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Cell E6 should be altered to reflect a different number of samples for more accurate calculations of the grand average and average range.
Cell E6 should be altered to reflect a different number of samples for more accurate calculations of the grand average and average range.
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The u-Chart for Nonconformances Per Unit Spreadsheet Template is designed for samples of equal size only.
The u-Chart for Nonconformances Per Unit Spreadsheet Template is designed for samples of equal size only.
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The formula to compute the average number of nonconformances per unit in a u-Chart is represented by the symbol 'u-bar'.
The formula to compute the average number of nonconformances per unit in a u-Chart is represented by the symbol 'u-bar'.
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The Control Chart Selection Control Chart Formula Summary provides guidelines on constructing x-bar and R-Charts.
The Control Chart Selection Control Chart Formula Summary provides guidelines on constructing x-bar and R-Charts.
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In the spreadsheet template example, the lower control limit (LCL) value is presented as 42.
In the spreadsheet template example, the lower control limit (LCL) value is presented as 42.
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The ISO standard 11462-1 addresses specific limitations of using x-bar and R-Charts for estimating process capability.
The ISO standard 11462-1 addresses specific limitations of using x-bar and R-Charts for estimating process capability.
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The purpose of updating the number of samples used in the calculations when deleting sample data is to maintain consistency in the dataset.
The purpose of updating the number of samples used in the calculations when deleting sample data is to maintain consistency in the dataset.
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Study Notes
Deleting Samples from Data Set
- When a sample is deleted from a data set in the templates, the number of samples used in the calculations should be updated to maintain consistency in the dataset.
Rescaling Vertical Axis of Charts
- Rescaling the vertical axis of the charts is done to improve the visualization of the data.
Out-of-Control Samples in X-Bar Chart
- Out-of-control samples in the x-bar chart have a common characteristic of being outside the control limits.
- Out-of-control samples in the x-bar and R-charts should be removed or corrected to maintain the process's integrity.
Purpose of Updating Number of Samples
- The purpose of updating the number of samples used in the calculations when deleting sample data is to maintain consistency in the dataset.
New Production Data and Revised Control Charts
- The new production data and revised control charts are used to monitor and control the process, ensuring it remains in control.
Constructing X-Bar and R-Charts
- The purpose of constructing x-bar and R-Charts in process monitoring and control is to monitor and control the process, ensuring it remains in control.
Estimating Process Capability
- Estimating process capability using control chart data is less accurate than using the complete set of data.
- To estimate process capability using x-bar and R-charts, one should collect between 25 and 30 samples, with sample sizes generally between 3 and 10.
Workers' Actions After Process is in Control
- After a process is determined to be in control, workers should continue using control charts to monitor performance and identify any special causes.
Importance of Worker Training
- Workers need to be trained to use control charts properly in process monitoring to ensure the process remains in control.
Calculating Process Capability Index
- The overall mean and average range are used in process capability index calculations.
Limitations of X-Bar and R-Charts
- One limitation of using x-bar and R-Charts for estimating process capability is that it is less accurate than using the complete set of data.
Modifying Formulas in Cells C9 and C10
- The formulas in cells C9 and C10 should be modified to use only the column range of the original data to ensure accurate calculations.
- The reason for modifying the formulas is to maintain consistency in the dataset.
Effect of Modifying Formulas
- Modifying the formulas in cells C9 and C10 affects the charting of the data.
ISO Standard 11462-1
- The ISO standard 11462-1 provides guidance for constructing and interpreting control charts for process monitoring and control.
- The standard addresses sample sizes effective for detecting process shifts of two standard deviations or larger.
- The standard does not provide guidance on defining the appropriate sample size for detecting process shifts.
U-Chart
- The purpose of a u-chart is to monitor the number of nonconforming units in a sample.
- When using a u-chart, the assumption is made that the data is from a Poisson distribution.
- The statistic used to compute the control limits for a u-chart is the average number of nonconformances per unit.
- The formula used to calculate the control limits for a u-chart is provided in the text.
- In the spreadsheet template example, the lower control limit (LCL) value is presented as 42.
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Description
Learn how to construct x-bar and R-charts, estimate process capability, calculate standard deviation using control chart data, compute sample means and ranges, and use these estimates in process capability index calculations.
