title: How to do a GLM when "contrasts can be applied only to factors with 2 or more levels"?
body: <p>I want to do a regression in R using <code>glm</code>, but is there a way to do it since I get the contrasts error.</p>
  
  <pre><code>mydf &lt;- data.frame(Group=c(1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12),
                     WL=rep(c(1,0),12), 
                     New.Runner=c("N","N","N","N","N","N","Y","N","N","N","N","N","N","Y","N","N","N","Y","N","N","N","N","N","Y"), 
                     Last.Run=c(1,5,2,6,5,4,NA,3,7,2,4,9,8,NA,3,5,1,NA,6,10,7,9,2,NA))
  
  mod &lt;- glm(formula = WL~New.Runner+Last.Run, family = binomial, data = mydf)
  #Error in `contrasts&lt;-`(`*tmp*`, value = contr.funs[1 + isOF[nn]]) :
  # contrasts can be applied only to factors with 2 or more levels
  </code></pre>