Difference between nominal and ordinal categorical variable?



I am currently studying about factors while studying it I have learnt that there is two type of categorical variable in which we can convert the character variable to a factor variable.

Nominal Categorical - without any particular implied order.

Ordinal Categorical - it occurs with a natural ordering.

I am not able to understand them clearly.

Why do we factorize variables in R ? What is the benefit of doing so?

Hi @sid100158,

Well let’s understand it with examples -

Nominal variable - Without any particular implied order like say color of eyes- Black, blue, green, brown. There is no ranking or ordering to the colors

Ordinal variable - Are categories with a natural ordering but the scale of difference is not defined. Example - Speed of a moving object - slow, medium, fast, super fast and ultra - fast. There is a natural ordering in it Slow < Medium < Fast < Super Fast < Ultra fast, but it does not imply that
Speed(Medium) - Speed(Slow) = Speed(Fast) - Speed(Medium)

Hope this helps.



There is also a special type categorical variable known as Dichotomous variables. They are nominal variables with only two categories; for example: Male or Female, Yes or No.