title: checking normality of residuals
body: <p>I am to test the normality of a set of residuals in a model</p>
  <pre class="lang-r prettyprint-override"><code>glm(Failure ~ Lead ,data=Exercise2, family=&quot;binomial&quot;)
  summary(glm(Failure ~ Lead ,data=Exercise2, family=&quot;binomial&quot;))
  
  hist(summary(glm(Failure ~ Lead ,data=Exercise2, family=&quot;binomial&quot;))$resi)
  </code></pre>
  <p>I have added the is.numeric to confirm my data is numeric</p>
  <pre class="lang-r prettyprint-override"><code>is.numeric(Exercise2$Lead)
  is.numeric(Exercise2$Failure)
  </code></pre>
  <p>The output i am getting is below</p>
  <blockquote>
  <p>Error in hist.default(summary(glm(Failure ~ Lead, data = Exercise2, family = &quot;binomial&quot;))$resi) :
  'x' must be numeric</p>
  </blockquote>
  <pre class="lang-r prettyprint-override"><code>&gt; is.numeric(Exercise2$Lead)
  [1] TRUE
  &gt; is.numeric(Exercise2$Failure)
  [1] TRUE
  </code></pre>
  <p>Can anyone advise why i am getting an error that data must be numeric when the data is numeric ?</p>