Rules For Detecting Signals
The most common sets are:
- The Western Electric rules
- The Wheeler rules (equivalent to the Western Electric zone tests)
- The Nelson rules
There has been particular controversy as to how long a run of observations, all on the same side of the centre line, should count as a signal, with 6, 7, 8 and 9 all being advocated by various writers.
The most important principle for choosing a set of rules is that the choice be made before the data is inspected. Choosing rules once the data have been seen tends to increase the Type I error rate owing to testing effects suggested by the data.
Read more about this topic: Control Chart
Famous quotes containing the words rules for, rules, detecting and/or signals:
“I invented the colors of the vowels!—A black, E white, I red, O blue, U green—I made rules for the form and movement of each consonant, and, and with instinctive rhythms, I flattered myself that I had created a poetic language accessible, some day, to all the senses.”
—Arthur Rimbaud (1854–1891)
“Let’s start with the three fundamental Rules of Robotics.... We have: one, a robot may not injure a human being, or, through inaction, allow a human being to come to harm. Two, a robot must obey the orders given it by human beings except where such orders would conflict with the First Law. And three, a robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.”
—Isaac Asimov (1920–1992)
“In our Mechanics’ Fair, there must be not only bridges, ploughs, carpenter’s planes, and baking troughs, but also some few finer instruments,—rain-gauges, thermometers, and telescopes; and in society, besides farmers, sailors, and weavers, there must be a few persons of purer fire kept specially as gauges and meters of character; persons of a fine, detecting instinct, who note the smallest accumulations of wit and feeling in the bystander.”
—Ralph Waldo Emerson (1803–1882)
“The term preschooler signals another change in our expectations of children. While toddler refers to physical development, preschooler refers to a social and intellectual activity: going to school. That shift in emphasis is tremendously important, for it is at this age that we think of children as social creatures who can begin to solve problems.”
—Lawrence Kutner (20th century)