There are four data measurement scales that include: nominal, ordinal, interval and ratio (Cooper , 2014). These measurement scales are used to categorize variables in different ways. If a variable is measured on the lowest nominal scale for example, red, blue, male, female, etc… arithmetic operations are not possible (Cooper , 2014). If a variable is measured on the nominal scale for example, rank order or the “bad, medium, good” type of data), arithmetic operations are possible due to a variable being designate such 1-4 being unhappy to happy (Cooper , 2014). Interval scales are numeric scales where the order is known as well as the exact differences between the values (Cooper , 2014). For example, when measuring data associated with temperature, the degrees of temperature are known (Cooper , 2014). However, There is no absolute zero which make determining a median or central tendency somewhat more difficult. Ratio scales are measurement scales that measure order, show exact values and have an absolute zero point (Cooper , 2014). An example of ratio variables can be seen in height to weight comparisons (Cooper , 2014).
Cooper , D. R. (2014). Business research methods (12ed.). New York, NY: McGraw-Hill/Irwin.