title: Using sjPlot in R to carry out wilcoxon-mann whitney on a factor variable
body: <p>I have two variables I want to compare: one containing a variable on age (continuous) and one containing a variable on stroke status (did or did not have stroke, factor).  I can do this happily using </p>
  
  <pre><code>wilcox.test (allcoding$age~allcoding$stroketia)
  </code></pre>
  
  <p>However, I struggle with doing this in <code>sjPlot</code> as it wants both to be numeric</p>
  
  <pre><code>sjt.mwu(mwu(allcoding$age, allcoding$stroketia))
  Performing Mann-Whitney-U-Test...
  ---------------------------------
  showing statistics between groups (x|y)
  Error in wilcox.test.default(xsub, ysub.n, paired = TRUE) :
   'y' must be numeric
  </code></pre>
  
  <p>How do I do the equivalent of the <code>"~"</code> in sjPlot rather than <code>","</code>?</p>
  
  <p>Thanks for the help</p>