title: factor() command in R is for categorical variables with hierarchy level only?
body: <p>I'm quite confused on when to use<blockquote>
  factor(educ)    or     factor(agegroup)   </blockquote>
   in R. Is it used for categorical ordered data? or can I just use to it a simple categorical data with no hierarchy?</p>
  
  <p>I know this is so basic. I really need some clarification. </p>