H

Histogram—7QC Tool

What Question(s) Does the Tool or Technique Answer?

How is the data of a process distributed; what does the data set look like? Are the data normally distributed?

A histogram helps you to

• Graphically display a data set to help indicate whether a process is distributed approximately normally.

• Determine the shape of the data—skewed or not, location of central tendency, spread.

• Analyze whether a process can meet customer requirements (that is, the spread). See AlsoProcess Capability Analysis,” p. 486.

• Understand if the output from two or more processes is different. (See AlsoHypothesis Testing,” p. 335)

Alternative Names and Variations

This tool is also known as

• Frequency plot

• Area chart

• Bar chart or bar graph ...

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