Example of Symmetry Plot

An engineer who is responsible for a cereal packaging line wants to characterize the package filling process and to determine whether the sample data come from a symmetric distribution. The engineer records the fill weights of 100 cereal boxes.

The engineer creates a symmetry plot to examine the symmetry of the data distribution.

  1. Open the sample data, CerealBoxWeight.MTW.
  2. Choose Stat > Quality Tools > Symmetry Plot.
  3. In Variables, enter Weight.
  4. Click OK.

Interpret the results

The data appear to be fairly symmetric. Notice the points below the line in the upper right corner of the symmetry plot. These points indicate a very slight diversion in the right side of the histogram. Because the points do not diverge from the line, the skewness in the data is mild.