title: Plotting fitted values vs observed ones in R or winbugs
body: <p>I want to plot the fitted values versus the observed ones and want to put straight line showing the goodness of fit. However, I do not want to use <code>abline()</code> because I did not calculate the fitted values using <code>lm</code> command as my I used a model that <code>R</code> does not cover. I calculated the coefficients and used them to calculate the fitted values. So, what can I do to obtain such a plot in R or in winbugs?</p>
  
  <p>Here is what I want </p>
  
  <p><img src="https://i.stack.imgur.com/1ft3W.png" alt="enter image description here"></p>