You can use a measure of center and a measure of variation to describe the distribution of a data set. The shape of the distribution can help you choose which measures are the most appropriate to use.

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Key Idea

 

Choosing Appropriate Measures

The mean absolute deviation (MAD) uses the mean in its calculation. So, when a data distribution is symmetric,

  • use the mean to describe the center and
  • use the MAD to describe the variation.

The interquartile range (IQR) uses quartiles in its calculation. So, when a data distribution is skewed,

  • use the median to describe the center and
  • use the IQR to describe the variation.

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