title: Integrated Discrimination Index (IDI) in Stata
body: <p>I'm getting two very different results for integrated discrimination improvement (IDI).</p>
  
  <p>If I use the nriidi.pkg package and run <code>idi</code> I get this output</p>
  
  <pre><code>    . idi totaloutcome grace_prob, prvars(allelecount)
  
  ----------------------------------------------------
        IDI |     Estimate     Std. Err.       P-value
   ----------+-----------------------------------------
             |     -0.01116       0.00430       0.00946
   ----------------------------------------------------
  </code></pre>
  
  <p>But when I use the <code>idi</code> from Mark Lunt's program</p>
  
  <pre><code> . net from http://personalpages.manchester.ac.uk/staff/mark.lunt
  
   . idi totaloutcome allelecount grace_prob
  
   Integrated Discrimination Improvement for allelecount = 0.0017
   Standard Error                                        = 0.0022
   z                                                     = 0.7615
   P-value (one-sided)                                   = 0.2232
   P-value (two-sided)                                   = 0.4464
  </code></pre>
  
  <p>Can anyone explain why this might be occurring or indicate why one package might be better than other?</p>