title: Perform an ANOVA for each individual level of a factor in R
body: <p>I am looking for a short and efficient method to run individual ANOVA analysis on each level of a factor. What I currently have, I think, is redundant and clutters the work space. Let's say I have the following:</p>
  
  <pre><code>Letter Number Question
  A      1      1
  A      2      1
  A      3      1
  B      1      1
  B      2      1
  B      3      1
  C      1      1
  C      2      1
  C      3      1
  </code></pre>
  
  <p>I could run the following code to split the data frame into subsets A, B, and C:</p>
  
  <pre><code>&gt; list2env(split(data, data$Letter), globalenv())
  &gt; ANOVA.A &lt;- aov(Question~Number, data=A)
  &gt; ANOVA.B &lt;- aov(Question~Number, data=B)
  &gt; ANOVA.C &lt;- aov(Question~Number, data=C)
  </code></pre>
  
  <p>While this provides me with the required results, it clutters the workspace. My actual data set is far larger, so I am seeking something simpler and more elegant.</p>