Variability describes how far apart data points lie from each other and from the center of a distribution. Along with measures of central tendency, measures of variability give you descriptive statistics that summarize your data.
Variability is also referred to as spread, scatter or dispersion. It is most commonly measured with the following:
Range: the difference between the highest and lowest values
A ratio scale is a quantitative scale where there is a true zero and equal intervals between neighboring points. Unlike on an interval scale, a zero on a ratio scale means there is a total absence of the variable you are measuring.
Length, area, and population are examples of ratio scales.
Ordinal data is classified into categories within a variable that have a natural rank order. However, the distances between the categories are uneven or unknown.
For example, the variable “frequency of physical exercise” can be categorized into the following:
There is a clear order to these categories, but we cannot say that the difference between “never” and “rarely” is exactly the same as that between “sometimes” and “often”. Therefore, this scale is ordinal.