3.2 CONTROL CHARTS FOR ATTRIBUTES

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ATTRIBUTE - a nonconformity that cannot, or will not be measured

NONCONFORMITY- A flaw in a product that will not always make it unsellable.

p-chart (for nonconforming units)

p-chart control limits can vary if the sample size varies.

np-chart (nonconforming units) - almost identical to p-chart, except not normalized to 0 to 1 scale, so it is more sensitive to sample size changes, but it is easier to maintain.

c-chart (for count of nonconformities) - Best used when there is a small number of errors in a huge sample space, and the nonconforming events are independent.

u-chart - similar to c-chart, except it can handle different sample group sizes (e.g. a rivet department dealing with different sizes of riveted parts).

choosing an attribute chart

READING: chapter 7, pg. 235-273

PROBLEMS: pg 273- #1, 4, 6, 9, 13, 18, 19, 21, 24