What is a numerical variable and what is a categorical variable?
A categorical variable is a category or type. For example, hair color is a categorical value or hometown is a categorical variable. Species, treatment type, and gender are all categorical variables.
A numerical variable is a variable where the measurement or number has a numerical meaning. For example, total rainfall measured in inches is a numerical value, heart rate is a numerical value, number of cheeseburgers consumed in an hour is a numerical value.
A categorical variable can be expressed as a number for the purpose of statistics, but these numbers do not have the same meaning as a numerical value . For example, if I am studying the effects of three different medications on an illness, I may name the three different medicines, medicine 1, medicine 2, and medicine 3. However, medicine three is not greater, or stronger, or faster than medicine one. These numbers are not meaningful.