title: Discrepancy in coefficient output from quantile regression
body: <p>If I run an ANOVA-style quantile regression model using only a categorical predictor, and if I specify a non-default fitting algorith, I receive different coefficient estimates from <code>summary.rq()</code> compared to <code>rq()</code> or <code>coef()</code>. Below is an example using the <code>engel</code> dataset:</p>
  <pre><code># Libraries
  library(data.table)
  library(quantreg)
  
  # Data
  data(engel)
  
  # Add Group
  setDT(engel)
  engel[,Group:=1L]
  engel[1:117,Group:=0]
  
  # Explore
  plot(foodexp~as.factor(Group),data=engel)
  
  # Fit
  fit=rq(foodexp~1+as.factor(Group),data=engel,tau=0.5,method='fn')
  fit
  # (Intercept) as.factor(Group)1 
  #   572.08066          18.40829 
  coef(fit)
  # (Intercept) as.factor(Group)1 
  #  572.08066          18.40829 
  summary(fit,se='nid')
  #                    Value     Std. Error t value   Pr(&gt;|t|) 
  # (Intercept)       572.08066  21.27472   26.89016   0.00000
  # as.factor(Group)1  18.40829  39.63886    0.46440   0.64279
  
  
  #### These coefs are different!
  summary(fit)
  #                    coefficients lower bd  upper bd 
  # (Intercept)       572.08066    525.92835 605.69257
  # as.factor(Group)1  16.43880    -34.51631  82.25984
  </code></pre>
  <p>In the above example, my estimated Group effect is 18.4 from <code>rq()</code> and <code>coef()</code>, but is 16.4 for <code>summary.rq()</code>.</p>
  <p>It appears that <code>summary.rq()</code> (which defaults to <code>se='rank'</code> for n&lt;1000) does not always recognize the specified fitting algorithm. Is this a bug?</p>