title: How is jitter determined in ggplot?
body: <p>I was looking over the <a href="http://docs.ggplot2.org/current/position_jitter.html">documentation</a> on jitter in ggplot while making some plots, and I realized that I don't really understand the argument.</p>
  
  <p>It states that the arguments are: </p>
  
  <p><code>Width:  degree of jitter in x direction. Defaults to 40% of the resolution of the data.</code> 
    and<br>
  <code>height: degree of jitter in y direction. Defaults to 40% of the resolution of the data.</code></p>
  
  <p>My question is, what exactly is resolution, and how is it determined?</p>
  
  <p>Also, you can override this and provide a value, like in the example below where we use 0.1:</p>
  
  <p><code>geom_point(position = position_jitter(w = 0.1, h = 0.1))</code></p>
  
  <p>What units belong to 0.1? Am I right to assume that this some proportion of the resolution?</p>