Hi, <div><br></div><div>Thanks. The mata lines of code did indeed add the cem library and fix the first error in Stata 10, but the second error remains in both versions. </div><div><br></div><div>The error is &quot;cem_weights not found r(111);&quot; and it follows attempts to run difference-in-differences regression after pre-processing the data with cem. Maybe there is a better syntax to run DND accounting for cem? I&#39;m telling Stata &quot;reg lblackproportion POLYEXAM YP YEAR [iweight=cem_weights].&quot;</div>
<div><br></div><div>Many thanks, </div><div>Katelyn</div><div><br><div class="gmail_quote">On Fri, Jun 29, 2012 at 7:41 PM, Matt Blackwell <span dir="ltr">&lt;<a href="mailto:blackwel@fas.harvard.edu" target="_blank">blackwel@fas.harvard.edu</a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
    <div>For the stata 10 code, one problem might be that Stata is</div><div>not finding the library. When you open up Stata, try running the</div><div>following line of code:</div><div><br></div><div>mata: mata mlib query</div>
<div><br></div><div>(with the colon and double-mata and everything) This should list some</div><div>libraries all starting with the letter l (&quot;el&quot;). One of the should be</div><div>&quot;lcem.&quot; If it isn&#39;t, try running this line of code (which may take a</div>
<div>bit):</div><div><br></div><div>mata: mata mlib index</div><div><br></div><div>Hopefully now you should see &quot;lcem.&quot; The program should work after</div><div>this. If this does not work, I have a few more ideas, but I think this</div>
<div>should resolve the issue.</div><div><br></div><div>For Stata 12, I think you have combined two separate commands. You want to run everything before &quot;reg&quot;. Should be the same command as in Stata 10. </div><div>
<br></div><div>Please let me know if this does not help.</div><div><br></div><div>cheers,</div><div>matt. </div><div><br></div><div><br></div><div>~~~~~~~~~~~</div><div>Matthew Blackwell</div><div>PhD Candidate</div><div>
Institute for Quantitative Social Science</div><div>Department of Government</div><div>Harvard University</div><div>url: <a href="http://people.fas.harvard.edu/~blackwel/" target="_blank">http://people.fas.harvard.edu/~blackwel/</a></div>
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    <p style="color:#a0a0a8">On Friday, June 29, 2012 at 3:55 PM, Katelyn Sack wrote:</p>
    <blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px">
        <div><div>Hi Matt &amp; all, <div><br></div><div>Thanks. My bad - that was a &quot;replicating my error&quot; error. Fixing it generates the following errors: </div><div>cem AGCYTYPE POPULATION region lblackproportion, tr(POLYEXAM)</div>

<div><div> &lt;istmt&gt;:  3499  cemStata() not found</div><div>r(3499);</div><div>(Stata 10 still seems to get stuck trying to find cem.)</div><div><br></div><div>And the same error as before in Stata 12:</div><div><div>

cem AGCYTYPE POPULATION region lblackproportion, tr(POLYEXAM)</div><div>reg lblackproportion POLYEXAM YP YEAR [iweight=cem_weights]</div><div>cem_weights not found</div><div>r(111);</div><div><br></div></div><div>Any other ideas how to troubleshoot?</div>

<div><br></div><div>Thanks and best, </div><div>Katelyn</div><div><br></div><br><div>On Fri, Jun 29, 2012 at 6:38 PM, Matt Blackwell <span dir="ltr">&lt;<a href="mailto:blackwel@fas.harvard.edu" target="_blank">blackwel@fas.harvard.edu</a>&gt;</span> wrote:<br>
<blockquote type="cite"><div>
    <div>
        Hi Katelyn,
    </div><div><br></div><div>Without taking too close a look, I think that the problem with the Stata 10 code is the space between &quot;tr&quot; and &quot;(&quot;. It should be &quot;<span>tr(POLYEXAM)&quot;. That might also be the problem in Stata 12. </span></div>

<div><span><br></span></div><div><span>Cheers,</span></div><div><span>Matt. </span></div><div><div>
     
      
    <p style="color:#a0a0a8">On Friday, June 29, 2012 at 1:39 PM, Katelyn Sack wrote:</p>
    </div></div><blockquote type="cite"><div>
        <div><div><div><div><div>Dear list, </div><div><br></div><div>When I try using cem in Stata 10,<b> </b>I get the error<b> &quot;</b>no variables defined in option treatment(), r(111);&quot; even though my syntax looks fine. (My command was &quot;cem  AGCYTYPE POPULATION region lblackproportion, tr (POLYEXAM).&quot;) The <a href="http://gking.harvard.edu/cem/" target="_blank">website</a> indicates it works in version 10. </div>


<div><br></div><div>When I try using it in Stata 12, I think the program gets a little farther. But I still get the error &quot;cem_weights not found&quot; after the commands:</div><div><div>cem  AGCYTYPE POPULATION region lblackproportion, tr (POLYEXAM)</div>


<div>reg lblackproportion POLYEXAM YP YEAR [iweight=cem_weights]</div><div><br></div><div>Any ideas how to troubleshoot? My best guess is that I skipped important pre-cem steps and the program is protesting that sort of human error. Perhaps the matched N (672) is too small and so I should simulate more data to produce more matches?</div>


<div><br></div><div>Many thanks, </div><div>Katelyn</div><div><br></div>-- <br><span style="font-family:arial,sans-serif;font-size:13px;border-collapse:collapse"><div>Katelyn Sack, Ph.D. candidate</div><div>University of Virginia </div>


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