Box-and-Whisker Chart

A box-and-whisker chart is a well-known statistical process control (SPC) tool that can help you eliminate process variations. Use this chart to compare and align products and processes, even on different lines or in different plants.

Like a histogram, box-and-whisker charts show data distribution. The leftmost point on each line (or whisker) represents the minimum value; the rightmost point represents the maximum value. The line in the center of each box represents the 50th percentile. The box itself spans from the 25th to the 75th percentile. The short lines to the left and right of the box represent the 5th and 95th percentiles.

Box and Whisker Plot Examples

Compare Multiple Process Streams

Whisker Plot Examples
Box-and-whisker charts are particularly useful for viewing multiple process streams. This capability can be especially useful in industries such as food packaging and beverage bottling, where minimum fill volumes and weights are typically regulated—and where overfill can significantly cost manufacturers.

In such environments, this chart will quickly reveal vital details:
  • Whether products are being filled to minimum required levels
  • What the average fill volume is
  • Where fills are exceeding required volumes or weights
With the box-and-whisker chart, you can easily compare processes or products to discover variances and determine outliers—which present problems and opportunities for improvement. Plus, you can examine in-spec data to find savings you might never have expected.

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See the Box-and-Whisker Plot in Excel

See the Box-and-Whisker Chart in Action

InfinityQS® SPC software solutions provide fast and easy access to box-and-whisker charts, without a great amount of time-consuming manual data entry or analysis. See how easy it can be to spot trouble—or opportunities—by surfacing this information from within SPC software. 


See how InfinityQS surfaces this information and makes SPC easy.
 

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