Demerit Chart

Posted on November 12, 2009 by

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Lately there have been problems in sampled batches of cookies from Katy’s Cookie Factory with the wrong amount of chocolate chips in the cookies, the wrong kinds of chips, and even stale chips. She wants to use a control chart to display how many non-conformities there are in each batch. However, she considers stale chips not as important as having the wrong amount of chips, and the wrong kind of chips as the biggest problem. So rather than simply count the non-conformities, she weights them and charts the weighted sum of non-conformities. Stale Chips is given a weight of 1, Wrong Amount of Chips is given a weight of 2, and Wrong Kind of Chips is given a weight of 3. So if there would be one problem of each, the weighted sum would be 6. She graphs these demerits on a control chart, making it a Demerit Chart (or simply a D-Chart). See the illustration below for the defects measured for a couple weeks and the corresponding D-Chart.

Demerit Chart

Posted in: Six Sigma