Misleading Graphs
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The document discusses various ways that graphs can be misleading, including not starting the scale at zero, using a small scale to exaggerate differences, omitting scale values or labels, using an incorrect scale, making pieces of a pie chart incorrect sizes, depicting objects as oversized relative to the actual scale differences, using images of different sizes in pictographs to misrepresent categories, and using non-standard graph shapes or sizes. The goal is to trick the viewer into misunderstanding the relationships or quantities being depicted.
Misleading Graphs
- 2. The most common “trick” with graphs is to make the scale not start at zero. This makes small differences look much bigger. Image Source: http://thinkingmeat.net
- 3. Sometimes the Scale does not start at zero, and the Graph is also put in a 3D perspective which confuses our eyes. Image Source: http://www.math6.org
- 5. The Scale does not start at zero, and makes the house price in 2006 look about seven times higher than 1975, when it is really only about two and a half times higher. (eg. 160 000 in 2006 is about 2.5 times 60 000 in 1975). Image Source: http://www.brickonomist.net
- 6. In Picture Graphs, the items are sometimes all made different sizes to trick our eyes into thinking we have more of the bigger sized items. Image Source: http://www.bbc.co.uk
- 7. In this Picture Graph, the year 2000 picture is about eight times bigger than the 1960 image. However when we check on the vertical scale, year 2000 is only two and a half times bigger. (2.5 x 100 = 250). Image Source: http://www.yale.edu
- 8. Trick or Treat ? In this Picture Graph, there is definitely a trick being done! From the vertical scale Michael collected about twice as much candy as Shayna, but his picture is about three times bigger. Image Source: http://www.yale.edu
- 9. This pie chart is totally incorrect. The sizes of the pieces of pie have not been drawn the right sizes. Image Source: http://www.visionjar.com
- 10. This non-standard pie chart is interesting. If “Cartera” was graphed properly as a piece of pie, then it would only be a very thin slither, and not nearly as big looking as the big circle drawn for it here. Image Source: http://dribbble.com
- 11. In this non-standard chart, it is very hard to work out what point they are trying to make or explain. Image Source: http://image.bayimg.com
- 12. The common ways to make a graph misleading are: • Scale not starting at zero. • Scale made very small to make graph look very big. • Scale values or labels missing from the graph. • Incorrect scale placed on the graph. • Pieces of a Pie Chart are not the correct sizes. • Oversized volumes of objects that are too big for the vertical scale differences they represent. • Size of images used in Pictographs being different for the different categories being graphed. • Graph being a non-standard size or shape.
- 13. Is this a Misleading Graph ? Image Source: http://mathspig.files.wordpress.com