SQC calculates and plots control charts for attribute and variable data.

Input requirements

The user enters:

• Title. A title for the analysis in the first input field
• Type of data. Select variable (measured data) or attribute (pass/fail) data type.
• Size of samples, n. Number of observations taken in each sample.
• Number of samples, m. The number of samples to use in constructing control limits.
• Engineering tolerance values (optional). The upper and lower specification limits for variable data. If provided, Six Sigma metrics will be displayed.
• Observations.
• Variable data. The observed data values for each sample are entered, free-form, in sample order. There should be at least mn values entered.
• Attribute data. The number of defective units (out of the n observed units) in each sample. There should be at least m values entered.
• In either case, additional sample observations may be included. The control limits will be calculated based on the first m samples and applied to all observations provided.

Pressing the Run SQC button initiates the analysis.

Sample variable data

The following 20 samples of size 5 may be copied and pasted into the Observations field:

36 35 34 33 32
31 31 34 32 30
30 30 32 30 32
32 33 33 32 35
32 34 37 37 35
32 32 31 33 33
33 33 36 32 31
23 33 36 35 36
43 36 35 24 31
36 35 36 41 41
34 38 35 34 38
36 38 39 39 40
36 40 35 26 33
36 35 37 34 33
30 37 33 34 35
28 31 33 33 33
33 30 34 33 35
27 28 29 27 30
35 36 29 27 32
33 35 35 39 36

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Sample attribute data

Defectives found in initial 30 samples of size 50:

12 15  8 10  4
 7 16  9 14 10
 5  6 17 12 22
 8 10  5 13 11
20 18 24 15  9
12  7 13  9  6

After removing some root causes, 24 additional samples of n = 50:

  9  6 12  5  6
 4  5  3  7  6
 2  4  3  6  5
 4  8  5  6  7
 5  6  3  4

Additional data sets

• Compression testing (x-bar, R)
• Dessicant weights (x-bar, R)

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