title: Error when estimating treatment effects with synth_runner
body: <p>I am using the <em>community-contributed</em> command <code>synth_runner</code> to estimate the treatment effect of a forest conservation policy, using time-series land cover data (three time periods).  </p>
  
  <p>I want to compare farms that enroll in the conservation program (treated in <code>t=3</code>) to a synthetic control. My dataset has ~<code>1500</code> observations, and I am using only <code>3</code> covariates per the code:</p>
  
  <pre><code>synth_runner percent_oldforest total_ha slope_mean dist_hwy, d(DID)
  </code></pre>
  
  <p>Variable <code>DID</code> is a dummy indicating treated or not in the last time period.  </p>
  
  <p>The model is taking ~<code>15</code> minutes to run and continually ends with the following error: </p>
  
  <blockquote>
    <p>Error estimating treatment effect for unit 363, or some other unit.</p>
  </blockquote>
  
  <p>I have increased my <code>matsize</code> to <code>2000</code> but this does not solve the problem.</p>
  
  <p>Is there a way to troubleshoot why there is an error and how I could identify and remove any observations that may generate this error?</p>