title: Find the mean and standard deviation of all values in a data frame
body: <p>I have a set of data frames each with different column names, e.g. <code>frameOne</code> looks like</p>
  
  <pre><code>   Q2  Q6  Q9
  1   1   0   0
  2   0   1   1
  ...
  N   1   1   0
  </code></pre>
  
  <p>and <code>frameTwo</code> is</p>
  
  <pre><code>   Q1  Q5  Q9 Q22
  1   1   1   0   1
  2   1   0   1   0
  ...
  N   1   1   1   0
  </code></pre>
  
  <p>How would I calculate the mean and standard deviation of the <em>entire frame</em> without explicitly stating the column names?</p>