<div class="figure" style="text-align: center">
<img src="figures/graphics-ColourHisto1-two-1.png" alt="Histograms of Martian height, separated according to nose colour (rows) and location (columns). Most of the red--nosed Martians came from Site II, whereas many of the blue-nosed Martians came from Site I. Therefore, geography is a confounding variable if we want to understand the association between height and nose colour. This is a graphical way to determine if geography is a confounding variable." width="548.031456" />
<p class="caption">(\#fig:ColourHisto1-two)Histograms of Martian height, separated according to nose colour (rows) and location (columns). Most of the red--nosed Martians came from Site II, whereas many of the blue-nosed Martians came from Site I. Therefore, geography is a confounding variable if we want to understand the association between height and nose colour. This is a graphical way to determine if geography is a confounding variable.</p>
</div>