title: The result of rpart is just with 1 root
body: <p>As in my dataset ,the Leakage have two value 1,0. There are just about 300 rows with 1 and extra in 569378 rows are with 1. This would be the reason that I just got 1 root in the rpart result.</p>
  
  <p>How can I solve this?</p>
  
  <pre><code>fm.pipe&lt;-Leakage~PipeAge +PipePressure
  
  &gt; printcp(CART.fit)
  
  Regression tree:
  rpart(formula = fm.pipe, data = Data)
  
  Variables actually used in tree construction:
  character(0)
  
  Root node error: 299.84/569378 = 0.00052661
  
  n= 569378 
  
           CP nsplit rel error xerror xstd
  1 0.0033246      0         1      0    0
  </code></pre>