Here&#x27;s a (brain) dead simple rule about pie charts:  if you&#x27;re using them to demonstrate a difference or change, so that you end up showing two, or more, pies, and if the aggregate amount represented by each pie isn&#x27;t equal, then you&#x27;re up to no good.  Even if you try to compensate by making one of the pies have a larger radius than the other this is bad, as area comparisons will always be under perceived.  If the case distinctions have the same summed aggregate, and you&#x27;re just showing how the apportioning of the groups have changed then you&#x27;re ok. But then graphically why not just have two bar charts which are visually more easy to interpret?