Excel Control Chartaka Statistical Process Control SPC Charts, Shewhart chart, quality control chart
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Bookmark = types
Types of Control Charts
Excel Control Charts to measure
discrete attributes
The most popular types of Statistical Process Control Charts are c-charts, p-charts, and u-charts,
which measure the number or ratio of non-conformances of a process or the thing being processed.
When you open the ControlChart.xls Excel template, and click the button to Open a Blank Template Sheet,
a dialog will appear asking which type of chart you want. Use this table to make your decision...
| C Chart | P Chart | U Chart | |
|---|---|---|---|
| Non-conformance data is measured in... | whole number integers (not fractions) | ||
| Sample Size... | can be unknown, or is ignored because always the same | can vary | can vary |
| The thing being being counted (on the vertical Y Axis) is... | the actual count of non-conformances | ratio of non-conformances divided by sample size | ratio of non-conformances divided by sample size |
| The test for defects... | must be a single pass/fail test per unit | must be a single pass/fail test per unit | can count multiple defects for each unit |
Even though it would have been easy to program, Systems2win has chosen not to offer the option of an np-chart,
because it is so rarely the right choice. An np chart is identical to a p chart, except that the Y vertical axis displays the actual count,
rather than the ratio. A p-chart is almost always the wiser choice.
Control Chart examples
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Process Control Charts to measure
continuous
variables
If your data is measured in fractions, rather than whole numbers,
then you need to use the XmR, XbarR, or XbarS types of control charts.These less popular tools consist of 2 to 4 graphs that must be interpreted together,
and require a level of training that starts to surpass the understanding of a typical Green Belt operator,
which is why Systems2win has chosen to only offer the more intuitive and widely-used Attribute Charts.If you need Variable Control Charts, then you should probably invest in software (and training) that is more targeted toward Six Sigma Black Belts - that have extensive training in advanced statistical methods.
If you're among the large majority looking for an easy-to-use and easy-to-understand c-chart, p-chart,
or u-chart, then you are likely to truly appreciate the consistent user interface, and high levels of
help and training that are common to all Systems2win templates.Even if you already own other statistical software, don't be surprised that many of your users might prefer the more professionally developed and better documented Systems2win templates. And (especially if you own a Systems2win license for unlimited users), perhaps you will find that you don't need to purchase and maintain so many seats of your expensive statistical software.
Bookmark = Training
Control Chart Training
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Make sure your sound is on Control Chart video
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How to use your Excel Control Chart template
Like every Systems2win template, there are succinct Instructions in the Help sheet,
and you can experiment with the sample data on the Sample sheet.
Rolling periods
Your Systems2win template makes it extremely easy to continue to enter or import unlimited data
while your chart displays only the most recent data for your specified Number of Rolling Periods...
and still correctly handle a Process Change
(where all of your control lines get reset because your process underwent a major change).
(We have never seen another control chart that offers this exceptionally useful feature)
The Update Chart button
If Is the Chart Updated? = FALSE
then you need to click the Update Chart button, which will:
- Update the chart for changes to your data
- Automatically scale the chart to show only:
- Either hide or show the +/- 1 and +/-2 Sigma chart lines -
based on whether Show All Chart Lines is TRUE or FALSE - Highlight points on your chart that violate your user-defined rules for Stability Analysis.
- Highlight the text of the Stability Analysis rule(s) that have been broken.
a. The most recent data for your specified Number of Rolling Periods
b. Rows that have data (correctly excluding blank rows from the chart)
Flat or Wavey Lines
In the p chart and u chart, you can define your own Flat Line Threshold ratio.
(the suggested default value is 75%)
If the minimum divided by the maximum Sample Size is greater than this ratio,
then Control Limits are charted as averaged flat lines.
If less, then they are charted as wavey lines -
showing how control limits change as sample size changes.
The Copy Chart button
Simply click the Copy Chart button
to copy a picture of your selected chart to the clipboard,
so you can then paste it to ANY other type of document
(such as Word, PowerPoint, etc.)
Or use the Systems2win Copy Sheet utility
to copy the entire worksheet to your Scorecard,
or any other type of Systems2win Excel document.
Multiple Languages
para gráficos de controle, gráficas de control, cartes de control, 控制图
Like every Systems2win Excel template,
your users can click a button to switch between languages.
International names for control charts include:
- c-chart: Gráfico c, Carta c, 图表 c
- p-chart: Gráfico p, Carta p, 图表 p
- u-chart: Gráfico u, Carta u, 图表 u
Bookmark = Reading
Suggested Reading and Resources for Quality Control Charts
Wikipedia: Introduction to Control ChartsRules for Stability Analysis: Nelson-Juran Western Electric
Control Chart templates
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This Excel template for control charting comes bundled
with
and you can empower every team member |
