The nominal scale is a measurement scale that lists names (categories.) Nominal data is discrete data and there is no particular order with a nominal measurement scale.
Use: Think of going to your favorite fast food restaurant. For example, the restaurant manager might list the first names of the employees, or might list the models of the cars that they drive. These are examples of a nominal measurement scale. You could put the names in alphabetical order, but the names really have no meaning of the rank order. When you think of nominal, think of the word ‘name’ – both start with an ‘N.’
Contrast the nominal scale with an ordinal scale where order does matter. When you think of ORDinal, think of the ORDer. For example, there might be a chute where the food items are awaiting a customer order. There are an equal number of containers of $0.99 fries, $3.00 burgers, $4.50 chicken sandwiches, and $6.99 super sandwiches. Order matters. The items are in order of cost and potential revenue loss if the orders are not fulfilled.
There is also the interval scale. The interval scale is like the ordinal scale except we can say the intervals between each value are equally split. Think of the temperature on a thermometer. The difference between 71 degrees and 72 degrees is the same as the difference between 31 and 32 degrees. The increments are in even intervals.
The ratio scale is an interval scale, but it does have a true zero point. Consider weight. There could be zero weight (none). The difference between four inches and five inches is the same as the difference between 72 inches and 73 inches, so in the ratio scale it is a type of the interval scale. The difference is the ‘zero’ is a possibility. Ratio and zero kind of rhyme. It’s just a way to remember – that’s all. Well, a thermometer has a zero? The zero on Fahrenheit scale or the Celsius scale is not a true zero point. Instead, the zero is a reference point to separate temperatures above and below zero. True zero, means no temperature at all. If the theory of absolute zero is true, where there is no heat, such as in deep outer space, then the thermometer would be a ratio scale.
