title: geom_smooth() what are the methods available?
body: <p>I'm using <code>geom_smooth()</code> from <code>ggplot2</code>.</p>
  
  <p>In Hadley Wickham's book ("ggplot2 - Elegant Graphics for Data Analysis") there is an example (page 51), where <code>method="lm"</code> is used. In the <a href="http://had.co.nz/ggplot2/geom_smooth.html" rel="noreferrer">online manual</a> there is no talk of the <code>method</code> argument. I see other Google results (and questions here) of people using <code>method='loess'</code>.</p>
  
  <p>Is there a an exhaustive list somewhere that explains the options?</p>
  
  <p>From what I can see, <code>'lm'</code> draws a straight line, and <code>'loess'</code> draws a very smooth curve. I assume there are others that draw more of a jagged line between reference points?</p>
  
  <p>The <code>se</code> argument from the example also isn't in the help or online documentation.</p>
  
  <p>FWIW here is my code.</p>
  
  <pre><code>p &lt;- ggplot(output8, aes(age, myoutcome, group=id, colour=year_diag_cat2)) +
    geom_line() + scale_y_continuous(limits = c(lwr,upr))
  p + geom_smooth(aes(group=year_diag_cat2), method="loess", size=2, se=F)
  </code></pre>