文档介绍：Graphical Methods
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Real World Scenario
Design: A superconducting designer needs to know the correlation between resistivity and temperature.
Manufacturing: A process engineer is monitoring the cable diameter for ignition wire sets.
Administrative: A customer service manager wants to know the distribution of customer claims as a function of claim value.
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Histogram
Dot Plot
Box Plot
Run Chart
Control Chart
Scatter Plot
Pareto Diagram
Cause and Effect Diagram
In this session, you will learn how to graphically analyze data, using these tools:
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Histogram
Histograms show how data is distributed. Open ‘.’
The Output Variable is DBP (used in the production of carbon black.) This represents 6 days of data collection, 12 hours per day.
In Minitab: Graph>Histogram, graph variable is DBP. Click “Options...” and specify “Number of intervals”= 8.
DBP Time Day
95 1 1
100 2 1
104 3 1
105 4 1
108 5 1
99 6 1
100 7 1
104 8 1
101 9 1
105 10 1
(The First Ten Observations)
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Dot Plot
A Dot Plot is another way of showing how data is distributed. Minitab displays the plot in the session window.
In Minitab: Graph>Character Graphs>Dotplot, variable is DBP.
Now try a Dotplot using Day as the by variable. What Information do you get?
: : : . .
: . : . : : :
. . . : : : : : : : : .
: : : : : : : : : : : : : : : :
---+---------+---------+---------+---------+---------+---DBP
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Box Plot
A Box Plot is a simpler way of showing how data is distributed. It is like a histogram, but plotted on its side.
Q1: 25%
Median
Q3: 75%
Graph>Boxplot, graph variable Y is DBP.
Graph>Boxplot, graph variable Y is DBP, variable X is Day.
lowest point within Q1-(Q3-Q1)
highest point within Q3+(Q3-Q1)
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Run Chart
Run charts are used to view