title: Strings as variable references in an R formula
body: <p>R newbie question here. I have a list called <code>dbdata</code>. Normally I use it like this:</p>
  
  <pre><code>myresults &lt;- rlm(V001 ~ V002+V003, data=dbdata)
  </code></pre>
  
  <p>However, I would like to make these references dynamic. I need to have something like this:</p>
  
  <pre><code>var1 &lt;- "V001"
  var2 &lt;- "V002"
  var3 &lt;- "V003"
  myresults &lt;- rlm(var1 ~ var2+var3, data=dbdata)
  </code></pre>
  
  <p>How would I reference the variables in the context of <code>rlm()</code>? I thought perhaps something like <code>eval()</code>, but that didn't work.</p>
  
  <p>Thanks!</p>