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Measures of Variation

A population is all the data that exist for a process. A sample is a small group of data randomly taken from a population that is representative of the whole population.

Measures of Variation Population

Three statistical measures of variation are:

Mean

  • The arithmetic average of the sample.
  • This measures the location of the process output.

Measures of Variation Mean

Range

  • The highest data point minus the lowest data point.
  • This is one of two measures of the variation in the process.

Standard Deviation

  • A statistic that measures how data cluster around the mean.
  • This is another measure of variation.
  • The smaller the standard deviation, the less variation there is in a process. The larger the standard deviation, the more variation there is in a process.

Measures of Variation Standard Deviation