title: Dealing with missing values for correlations calculation
body: <p>I have huge matrix with a lot of missing values. I want to get the correlation between variables.</p>
  
  <p><strong>1.</strong> Is the solution   </p>
  
  <pre><code>cor(na.omit(matrix))
  </code></pre>
  
  <p>better than below?</p>
  
  <pre><code>cor(matrix, use = "pairwise.complete.obs")
  </code></pre>
  
  <p>I already have selected only variables having more than 20% of missing values.</p>
  
  <p><strong>2.</strong> Which is the best method to make sense ?</p>