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So, a process may be predictable
but not capable.
Se en Common tools
SPC takes numbers and presents the numbers pictorially in order to tell a story. The
story that is told demonstrates what is happening within the process. That story is
often called ???the voice of the process.??? The pictures produced must be explained
and must be accurate. To that end, there are seven commonly recognized tools for
statistical process control. They are the:
Check sheet
Run chart
Histogram
Pareto chart
Scatter diagram/chart
Cause and effect or fishbone diagram
Control chart
n n n n n n n
238 n Interpreting the CMMI
Some basic examples follow. These examples are for illustration only; we don??™t
go into how to derive the values for each chart and then how to translate the values
into meaningful representations.
Check Sheet
The check sheet, shown in Table 18.1, is used for counting and accumulating
data.
Run Chart
The run chart, shown in Figure 18.1, tracks trends over a period of time. Points are
tracked in the order in which they occur.


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