title: How to increase size of the points in ggplot2, similar to cex in base plots?
body: <p>I have the following dummy code:</p>
  
  <pre><code>dt&lt;-data.frame(country=letters[1:20],val=rnorm(20),siz=rnorm(20))
  qplot(x=country,y=val,data=dt,geom="point",size=siz)
  </code></pre>
  
  <p>Now I want to increase the relative size of the points, since the resulting smallest point is too small. Is this possible to do by changing one parameter, like <code>cex</code> in base plots?</p>