title: Stata: xtunitroot
body: <p>I need to check if inflation is a stationary variable or not. To check this I want to use <code>xtunitroot</code> command (in Stata). I first set my cpij(inflatation variable) over a time variable(tv):</p>
  <pre><code>xtset cpij tv
  
  panel variable:  cpij (unbalanced)
  time variable:  tv, 1 to 245, but with gaps
          delta:  1 unit
  </code></pre>
  <p>Then I run
  <code>xtunitroot llc cpij</code></p>
  <p>But I get
  <em>Levin-Lin-Chiu test requires strongly balanced data</em></p>
  <p>How can I fix this problem?</p>
  <p>I have tried</p>
  <pre><code>xtunitroot fisher cpij, dfuller lags(1)
  </code></pre>
  <p>But I get</p>
  <pre><code>performing unit-root test on first panel using the syntax
  
  dfuller cpij, lags(1) 
  
  returned error code 2000
  
  r(2000);
  </code></pre>