title: deleting observations based on date
body: <p>I am trying to delete all observations with date before 02/27/12.  The output data set was exactly the same as the original one, but it certainly should not be.</p>
  
  <pre><code>data new1;
  set new;
  if service_start_date &lt; '02/27/12' or date_of_first_revenue_from_acti &lt; '02/27/12'   then delete;
  run;
  </code></pre>