title: how to create a continuous variable?
body: <p>I have a continuous dataset that looks like this:</p>
  <pre><code>df &lt;- data.frame(age = c(1, 2, 3, 4, 5, 6, 7))
  </code></pre>
  <p>1 is 13 y/o, 2 is 14 y/o, 3 is 15 y/o, 4 is 16 y/o, 5 is 17 y/o, 6 is 18 y/o, 7 is 19 y/o.</p>
  <p>How can I replace <code>c(1:7)</code> to <code>c(13:19)</code> so that I can find the mean and SD of age in this dataset.</p>