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.
Three statistical measures
of variation are:
Mean—The arithmetic average of the sample.
This measures the location of the process output.
Range—The highest data point minus the lowest data point. This
is one of two measures of the variation in the process.
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.