Example of Individuals chart
main topic     interpreting results     session command     see also 

In the following example, Weight contains the weight in pounds of each batch of raw material.

1    Open the worksheet EXH_QC.MTW.

2    Choose Stat > Control Charts > Variables Charts for Individuals > Individuals.

3    In Variables, enter Weight.

4    Click I Chart Options, then click the Tests tab.

5    Choose Perform all tests for special causes, then click OK in each dialog box.

Session window output

I Chart of Weight

 

 

 

Test Results for I Chart of Weight

 

 

TEST 1. One point more than 3.00 standard deviations from center line.

Test Failed at points:  14, 23, 30, 31, 44, 45

 

TEST 2. 9 points in a row on same side of center line.

Test Failed at points:  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 33,

                        34, 35, 36

 

TEST 5. 2 out of 3 points more than 2 standard deviations from center line (on

     one side of CL).

Test Failed at points:  24, 30, 31, 45

 

TEST 6. 4 out of 5 points more than 1 standard deviation from center line (on

     one side of CL).

Test Failed at points:  5, 6, 7, 29, 30, 31, 32, 45

 

* WARNING * If graph is updated with new data, the results above may no

          * longer be correct.

Graph window output

 

Interpreting the results

The individuals chart shows six points outside the control limits and 22 points inside the control limits exhibiting a nonrandom pattern, suggesting the presence of special causes. See the Session window results for a list of the points that failed each test.