title: Meaning of "I" in the R Language
body: <p>Naturally, I had little success searching Google for "R I", "I in R", and "R language I". </p>
  
  <ul>
  <li>The <a href="http://stat.ethz.ch/R-manual/R-devel/library/base/html/AsIs.html">R help</a> says "Change the class of an object to indicate that it should be treated ‘as is’.". </li>
  <li>My O'Reilly R book doesn't have an entry for it in its index. </li>
  <li>My Cambridge book essentially says, about "I(logdist^2)": "ensures that is taken as the square, rather than as an interaction of logdist". </li>
  </ul>
  
  <p>Can someone explain the "interaction" comment? Can someone explain why "logdist^2" wouldn't be interpreted in the traditional way?</p>