title: R cluster analysis and dendrogram with correlation matrix
body: <p>I have to perform a cluster analysis on a big amount of data. Since I have a lot of missing values I made a correlation matrix. </p>
  
  <pre><code>corloads = cor(df1[,2:185], use = "pairwise.complete.obs")
  </code></pre>
  
  <p>Now I have problems how to go on. I read a lot of articles and examples, but nothing really works for me. How can I find out how many clusters are good for me?</p>
  
  <p>I already tried this:</p>
  
  <pre><code>dissimilarity = 1 - corloads
  distance = as.dist(dissimilarity) 
  
  plot(hclust(distance), main="Dissimilarity = 1 - Correlation", xlab="") 
  </code></pre>
  
  <p>I got a plot, but its very messy and I dont know how to read it and how to go on. It looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/P3kBi.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/P3kBi.png" alt="enter image description here"></a></p>
  
  <p>Any idea how to improve it? And what can I actually get out of it?</p>
  
  <p>I also wanted to create a Screeplot. I read that there will be a curve where you can see how many clusters are correct.</p>
  
  <p>I also performed a cluster analysis and choose 2-20 Clusters, but the results are so long, I have no idea how to handle it and what things are important to look on. </p>