Statistical Process Control online Calculator

With the SPC Online Calculator you can easily input data and get accurate Statistical Process Control results without the complexity of traditional software. You can create the following control charts online with numiqo:

• I Chart Maker
• I-MR Chart Maker
• Xbar Chart Maker
• Xbar-R Chart Maker
• Xbar-S Chart Maker
• P Chart Maker
• NP Chart Maker
• C Chart Maker
• U Chart Maker

Therefore, to use the statistical process control online calculator simply copy your data into the table above.

Tests for special causes

A control chart can be checked with up to eight tests for special causes (also known as Nelson rules). numiqo marks every point that fails a test in red, writes the number of the test next to it and lists the failed tests with their points below the chart. These are the eight tests:

1. 1 point is more than 3 standard deviations away from the center line
2. 9 points in a row on the same side of the center line
3. 6 points in a row, all increasing or all decreasing
4. 14 points in a row, alternating up and down
5. 2 out of 3 points are more than 2 standard deviations from the center line (same side)
6. 4 out of 5 points are more than 1 standard deviation from the center line (same side)
7. 15 points in a row within 1 standard deviation of the center line (either side)
8. 8 points in a row are more than 1 standard deviation from the center line (either side)

Under "Tests" next to the chart you choose which of them are run:

• None: no tests are run.
• Basic (1): only test 1, a point beyond the control limits. This is the default.
• Standard (1, 2, 5, 6): the four Western Electric rules, the usual set for finding smaller shifts of the process.
• All (1-8): all eight tests.

Every additional test finds small changes earlier, but also gives more false alarms on a stable process: with test 1 alone about one false alarm in 370 points, with the four Western Electric rules about one in 92. Therefore start with Basic and add tests when you want the chart to be more sensitive.

Not every chart has all eight tests:

• I chart and Xbar chart: tests 1 to 8.
• R chart, S chart and the attribute charts (P, NP, C, U and the Laney charts): tests 1 to 4. Standard runs tests 1 and 2 there, All tests 1 to 4.
• MR chart: only test 1. Each value is part of two consecutive moving ranges, so the moving ranges are not independent and form runs even when the process is stable.

The standard deviation in the tests is the one behind the control limits: the limits lie 3 standard deviations from the center line. With several stages every stage is tested on its own.

Of course, you can also calculate the process capability with the cpk calculator.

Key Features:

• User-Friendly Interface: No steep learning curve here! Our calculator is easy to use, even if you're not a statistician.
• Graphical Outputs: View control charts, histograms, and other important graphics that make interpreting your data straightforward and effective.
• Secure and Confidential: Your data stays private. Process your calculations with the assurance of top-tier data security.

How It Works:

1. Enter Your Data: Input your measurement data directly or upload your data file.
2. Select Your Analysis: Choose the type of SPC analysis you need from our comprehensive suite of tools.
3. Get Instant Results: Our calculator processes your data and provides detailed results and graphical representations in seconds.

Who Can Benefit?

• Quality Control Teams: Maintain the highest standards of product quality through continuous monitoring.
• Production Managers: Optimize your manufacturing processes based on reliable statistical insights.
• Data Analysts: Access advanced statistical tools for in-depth analysis without any specialized software.