## What is a Measurement Variable?

A measurement variable is a variable that can be measured and given a number, like 4 mm, 3 yards or 42. Measurement variables are sometimes called numeric variables. More formally, measurement variables are called quantitative variables. Which term you use is usually a matter of personal choice although**in academic writing (especially in journals) the term**

*quantitative variable*is usually preferred.Measurement variables can be continuous, discrete, interval or ratio variables.

**Discrete variables**are countable and finite (i.e. they have an end). An example of a discrete variable is numbers on a birthday card: 1,2, 21, 40, 50, 60 and so on.**Continuous variables**are not countable as they have infinite possibilities. If you did try to count them you would be counting on and on until infinity. Weight is an example of a continuous variable. A Weight can be 20lbs, or 20.1 lbs or 20. 00000001 lbs…and so on.

**Note:***For more examples of the difference between discrete and continuous variables, see:*.**Discrete vs. Continuous variables****Interval variables**: a subset of continuous variables where measurements fall on a scale with meaningful intervals (like a thermometer).**Ratio variables**: also a subtype of continuous data, it is a type of interval variable that has a meaningful zero. For example, 0 years old means that you don’t exist.

## Other broad types of variables

**Nominal variables**: variables than can be placed into categories like male/female, young, adult, senior or freshman/sophomore/junior/senior. If you only have two measurement variables (e.g. under 18, 18 and over), and if you are analyzing your data (e.g. you’re performing a hypothesis test), it may make more sense to treat your measurement variables as nominal variables.**Ranked variables**: variables that are ranked in order like 1st, 2nd, 3rd…

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