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Each point represents an observation. You
can often see interesting trends in the data by simply plotting data on a run chart. A
Student Name
Jane
Robert
Jennifer
Pu?¬? Daddy
In Class is Week?
table 18.1 Check Sheet
??“0
2
4
6
8
10
12
14
8/6/068/13/068/20/068/27/069/3/069/10/069/17/069/24/0610/1/0610/8/0610/15/06
10/22/0610/29/0611/5/0611/12/0611/19/06
11/26/0612/3/06
Weeks Before Product Delivery
Number of Empty Pizza Boxes
Figure 18.1 run chart.
Statistical Process Control n 239
danger in using run charts is that you might overreact to normal variations, but it is
often useful to put your data on a run chart to get a feel for process behavior.
Histogram
The histogram, shown in Figure 18.2, is a bar chart that presents data that have
been collected over a period of time and graphically presents these data by frequency.
Each bar represents the number of observations that fit within the indicated
range. Histograms are useful because they can be used to see the amount of
variation in a process. The data in the histogram in Figure 18.


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