**Numerical** (quantitative) variables have magnitude and units, with values that carry an equal weight. For example, the difference between 1 and 2 on a numeric scale must represent the same difference as between 9 and 10. There are two major scales for numerical variables:

**Discrete**variables can only be specific values (typically integers). For example:- number of siblings
- year of birth

**Continuous**variables can take on any real number value. For example:- height
- temperature

**Categorical** (qualitative) variables have values that describe labels or attributes. Even if the categories can be placed in a natural order, they have no magnitude or units. There are two major scales for categorical variables:

**Nominal**variables have categories with no distinct or defined order. For example:- gender
- favorite color
- nationality

**Ordinal**variables have an inherent order. For example:- Likert scales (strongly disagree, disagree, neutral, agree, strongly agree)
- t-shirt size (small, medium, large)

*Note: *Ordinal categorical variables are often aggregated to create scales in humanities research and can be treated as numeric if they have a sufficient amount of variation in values.