Where is the coefficient of variation used?
The most common use of the coefficient of variation is to assess the precision of a technique. It is also used as a measure of variability when the standard deviation is proportional to the mean, and as a means to compare variability of measurements made in different units.
What does the range tell us?
The range can only tell you basic details about the spread of a set of data. By giving the difference between the lowest and highest scores of a set of data it gives a rough idea of how widely spread out the most extreme observations are, but gives no information as to where any of the other data points lie.
When would you use range?
This can be useful if you are measuring a variable that has either a critical low or high threshold (or both) that should not be crossed. The range will instantly inform you whether at least one value broke these critical thresholds. In addition, the range can be used to detect any errors when entering data.
Why is it better to use the median than the mean?
In these situations, the median is generally considered to be the best representative of the central location of the data. The more skewed the distribution, the greater the difference between the median and mean, and the greater emphasis should be placed on using the median as opposed to the mean.