One warning about pie charts in many visualization applications today is you are often looking at how the terms in the chart relate to each other. Not over the

One warning about pie charts in many visualization applications today is you are often looking at how the terms in the chart relate to each other. Not over the set of all terms. If I want to draw a pie chart of the top-5 terms for some field and the chart represents just those terms, then the chart represents how they compare against each other - not necessarily how those top-5 terms compare against the entire set. I know, sounds obvious but I've seen data misinterpreted because of this. The pie chart must represent the entire set and if you're plotting a subset of the data in the chart and ignoring the rest then your visualization may not say what you think it says.