title: Significant differences between multiple variables in R
body: <p>I have a dataset of particle concentrations recorded at 5 different height. I want to find out whether the differences are significant. For each height, N=15.</p>
  <p>What test would be appropriate to use?</p>
  <p>I used pairwise.t.test, but am not sure if this is the right solution, as sampling size is quiet small.
  I also tried pairwise.wilcox.test which returns different p-values and errors &quot;cannot compute exact p-value with ties&quot;. Is this due to the small sampling size and can I use it?</p>
  <p>mydata:</p>
  <pre><code>structure(list(height = c(1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 
  5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 
  1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 
  2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 
  3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 4L, 5L, 1L, 2L, 3L, 
  4L, 5L), values = c(1.67, 3.33, 6.67, 10, 15, 25, 20, 11.67, 
  16.67, 18.33, 1.67, 0, 1.67, 5, 3.33, 5, 73.33, 8.33, 5, 5, 10, 
  5, 6.67, 6.67, 3.33, 18.33, 18.33, 6.67, 38.33, 0, 23.33, 10, 
  15, 11.67, 5, 11.67, 8.33, 1.67, 15, 3.33, 13.33, 10, 10, 3.33, 
  10, 8.33, 21.67, 10, 41.67, 8.33, 3.33, 36.67, 15, 11.67, 8.33, 
  8.33, 8.33, 5, 5, 0, 1.67, 8.33, 16.67, 3.33, 10, 16.67, 8.33, 
  8.33, 25, 1.67, 6.67, 26.67, 3.33, 11.67, 1.67)), row.names = c(NA, 
  -75L), class = &quot;data.frame&quot;)
  </code></pre>