Question

I'm a little confused regarding types of data & measurement scales for statistics, including: Nominal, Ordinal, Interval and Ratio.

If one were to categorize class standing, (1=freshmen, 2=sophomore, 3=junior and 4=Senior) would this be considered Nominal, Ordinal or interval? and why?

Answer 1

There are mainly 4 measuring scales in statistics. Two each for categorical and continuous variables.

The categorical scale of measurements are 'Nominal' and 'Ordinal'.

The difference between them is that Nominal scale doesn't have any order among its categories while Ordinal does.

For example, color of roses (i.e. Red, Pink, White) is measured on Nominal scale as the color doesn't have any ranking order. While your grades (out of A, B, C, D) is measured on an ordinal scale as it has an order. A represents a better grade than B and so on.

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Then there is two type of scale for continuous data namely 'Interval' and 'Ratio' scale. The difference between them is that 'Interval' ratio doesn't have a true '0' value. While the Ratio scale does have a zero value.

For example the temperature on celsius scale being 0 doesn't make sense if we say that it means there is no temperature at all. Its actually a relative measure. So, being 0 doesn't give us anything certain and realistic.

On the other hand, weight of an oobect being 0 essentially means that there is no mass at all. So, being 0 here is significant.

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Now, first of all note that the variable you have i.e. 'Class Standing' is a categorical variable as there are only 4 possible values that it can take.

Now, as these values have an order, so it must be an Ordinal Scale measurement.

The classes have seniority heirarchy. So there is an order. Hence, Ordinal.