title: Scatterplot with single regression line despite two groups using ggplot2
body: <p>I would like to produce a scatter plot with ggplot2, which contains both a regression line through all data points (regardless which group they are from), but at the same time varies the shape of the markers by the grouping variable. The code below produces the group markers, but comes up with TWO regression lines, one for each group.</p>
  
  <pre><code>#model=lm(df, ParamY~ParamX)
  p1&lt;-ggplot(df,aes(x=ParamX,y=ParamY,shape=group)) + geom_point() + stat_smooth(method=lm)
  </code></pre>
  
  <p>How can I program that?</p>