Some of the charts coming out during this PH election have been excellent. The chart you see in Exhibit A isn’t one of them. In fact this chart, which got 10k shares on social media, is straight up lying.
The purpose of a chart is to show the data. I.e. To help the audience better understand the relative magnitudes of the numbers selected.
Class ABC has a population size of 3.7 million. Class D has a population size of 48.2 million. Divide the latter by the former and we see that Class D is 13x larger in population than Class ABC.
Class ABC’s population is represented by the size of the blue triangle. Class D’s population is represented by the size of the red shape (this shape is known as an ‘isosceles trapezoid’, for those who wanted a useless fact for the day).
Since charts should faithfully represent the data, the red shape should be 13x larger than the blue triangle, since the number underlying the red shape is 13x larger than the number underlying the blue triangle. I suspected that this wasn’t the case, so I decided to use PowerPoint to cut out the blue triangle and see how many of them I could fit inside the red shape (Exhibit B). (No I don’t recommend aspiring to this level of petty and yes I am aware that this sort of behavior is probably classified in the DSM 5)
So, how many blue triangles did I fit inside the red shape? 146, with room to spare. So the chart is visually implying that Class D is at least 146x larger than Class ABC, when in reality, Class D is 13x larger than Class ABC.
Thanks to Adrian Aguilar for sending this chart in for comment.
Note: I am not saying that the creator of the chart intended to lie. People unwittingly produce charts that tell lies all the time. The purpose of this post is to draw attention to the caution one must take when interpreting charts that show numbers represented as areas.
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