title: Using ROCR package difficulties
body: <p>I'm following an analysis of German Credit data and I got an error which I'm failing to rectify because I already installed the <strong>ROCR</strong> package. Below is the code that uses the <strong>ROCR</strong>:</p>
  
  <pre><code>#load library
  library(ROCR)
  
  #score test data set
  test$score &lt;- predict(m,type='response',test)
  pred &lt;- prediction(test$score,test$good_bad)
  perf &lt;- performance(pred,"tpr","fpr")
  plot(perf)
  </code></pre>
  
  <p>Now, after running <code>pred</code>, I get the following error:</p>
  
  <pre><code>&gt;pred &lt;- prediction(test$score,test$Good_Bad)
  Error: could not find function "prediction".
  </code></pre>
  
  <p>This also happens when I try to execute the following line:</p>
  
  <pre><code>&gt;perf &lt;- performance(pred,"tpr","fpr")
  Error: could not find function "performance"
  </code></pre>