title: How do I get a straight line from ggplot and am I doing something wrong?
body: <p>I am very new to R and I am working on a voluntary project to predict some parameters based on similar observations for several categorical types. For example, same parameters for different people, but of course, different values for each person. </p>
  
  <p>I got this output from ggplot:</p>
  
  <p><a href="https://i.stack.imgur.com/BAEGm.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/BAEGm.jpg" alt="enter image description here"></a></p>
  
  <p>My questions are:</p>
  
  <ol>
  <li><p>How do I get this to plot a straight line?</p></li>
  <li><p>From this plot, does it appear I am doing something wrong and if so, is it related to the lm function?</p></li>
  </ol>