Though ordinal scales can be ranked or ordered, the distance between points varies. With nominal and ordinal measures, the mode can be a helpful measure of central tendency . We find the same distance between each possible value. Examples are number of children, age, and test scores. These variables have a distinct and meaningful zero-point.
Examples are temperature or distance measurements.
In order to take advantage of more powerful statistical methods that can not be used at the categorical-nominal level, however, we assign a numeric value to these categories. Statistics is mostly the manipulation of numbers. Names are not numbers. T he level of measurement helps us decide how to interpret the data from that variable. Knowing the level of measurement helps us to decide what statistical analysis is appropriate.