title: Is this boxplot notch correct?
body: <p>Need an explanation for this weird looking boxplot notch.
  I've provided the data and the code before plotting (using <code>ggplot2</code>)</p>
  <p>The notch looks inverted on top. How can this be explained?
  I've never encountered a notch like this.</p>
  <p><img src="https://i.stack.imgur.com/8azC4.png" alt="weirdnotch" /></p>
  <pre><code>df&lt;-read.table(text =   '   SU AGC.low    AGB
  1   1   22.12  48.09
  2   2   10.14  22.04
  3   3   18.23  39.63
  4   4   36.14  78.57
  5   5   47.56 103.39
  6   6   38.98  84.74
  7   7   47.74 103.78
  8   8   15.17  32.98
  9  10   30.24  65.74
  10 11   33.28  72.35
  11 15   40.27  87.54', header=TRUE, sep=&quot;&quot;)
  
  df = subset(df, select = -c(AGC.low))
  
  dfm &lt;- melt(df[,c('SU','AGB')],id.vars = 1)
  str(dfm)
  dfm$SU&lt;-as.factor(dfm$SU) #dit is ook nodig voor collaps x - as 
  
  view(dat)
  view(dfm)
  
  # Make a boxplot for AGB
  # Trim data frame 
  # Remove SU column 
  box_dfm = subset(dfm, select = -c(SU))
  names(box_dfm)
  names(box_dfm)[2] &lt;- &quot;AGB&quot; 
  #names(box_dfm)[1] &lt;- &quot;AGB&quot; 
  
  library(ggplot2)
  # Change outlier, color, shape and size
  p&lt;-ggplot(box_dfm, aes(x=variable, y=AGB, color=variable)) + 
    geom_boxplot(outlier.colour=&quot;black&quot;, outlier.shape=20,outlier.size=2,notch=TRUE)+
    scale_y_continuous(breaks=seq(0,160,20))+
    ggtitle(&quot;Plot scale Biomass&quot;) +
    xlab(&quot;Variable&quot;) + ylab(&quot;Biomass Mg B/ ha&quot;)+
    theme(legend.position=&quot;none&quot;)
  
  </code></pre>