title: Test to compare percentage/proportions between groups in R
body: <p>I have cell type proportions for 7 different cells, which sum up to 100% for every person (it's an estimate of cell type composition).</p>
  <p>An example is something like this:</p>
  <pre><code>data1 &lt;- rbind(c(0.2, 0.2, 0.5, 0.025, 0.025, 0.025, 0.025), c(0.1, 0.15, 0.6, 0.0375, 0.0375, 0.0375, 0.0375))
  
  data2 &lt;- rbind(c(0.3, 0.25, 0.4, 0.01, 0.01, 0.01, 0.02), c(0.25, 0.3, 0.4, 0.01, 0.001, 0.01, 0.029))
  </code></pre>
  <p>Where rows would correspond to persons and columns to the cell types. In this example we would have 2 data sets with 2 persons each.</p>
  <p>In reality, I have 2 or 3 data sets with different number of persons (around 400 and around 100).</p>
  <p><strong>I want to test, if the proportion of cell types is different <em>between the data sets</em>.</strong></p>
  <p>How could I do this in R?</p>
  <p>I've read other posts with somewhat related questions. One thing suggested was logistic regression, but isn't this problematic as the &quot;predictors&quot; (cell types) are <strong>dependent</strong>, as they sum up to 100%?</p>