©G Dear 2010 – Not to be sold/Free to use Displaying Single Data Sets Applied Mathematic (Preliminary General 1) Misleading Graphs Stage 6 - Year 11 Press Ctrl-A ©G Dear 2010 – Not to be sold/Free to use

In the business world we don’t want to create misleading graphs Three types (of many) are: 50 60 70 80 1. Displaced Axes. Does not start at zero. 2. Exaggerated Area or Vol. 10 20 30 Size exaggerates the difference. 10 100 1000 3. Displaced Axes. Axes are irregularly numbered. End of Slide 2

The increase in price was not as big as it appeared to be. Misleading Graphs Displaced Axes Massive Increase In House Prices this Year 82 000 80 000 60 000 Average House Price 81 000 Average House Price 40 000 80 000 20 000 1998 1999 1998 1999 Year Year The increase in price was not as big as it appeared to be. End of Slide 3

Misleading Graphs Displaced Axes 1000 1000 995 900 990 800 985 700 980 600 Number of Votes Number of Votes 975 500 970 400 965 300 960 200 955 100 950 Pizza Hot Dogs Hamburgers Pizza Hot Dogs Hamburgers Favourite Food Favourite Food The number of votes appears significantly here. The number of votes appears not so significantly here. End of Slide 4

Misleading Graphs Exaggerated use of Area or Volume. Number of Singles Sold Number of Singles Sold 1995 1996 1997 1998 1998 1997 1996 1995 The Brown column looks bigger than the purple column. . But is it? End of Slide 5

The Exaggerated use of Area or Volume. Misleading Graphs The Exaggerated use of Area or Volume. Key: 50 Key: 50 Dog: Cat: Horse: This is bad. The various sized pictures distorts the graph. Dog: Cat: This is much better Horse: All pictures must be the about the same size. (Area) End of Slide 6

Exaggerated use of Area or Volume. Misleading Graphs Exaggerated use of Area or Volume. Sales at Gerry’s Milkbar have doubled from 2007 to 2008. 2007 2008 The 2008 volume is eight times bigger than the 2007 volume. End of Slide 7

Source: www.scribd.com/doc/19047168/19-Misleading-Graphs Irregular Scale Axes Source: www.scribd.com/doc/19047168/19-Misleading-Graphs 1993, 1996 and 1998 are missing. End of Slide 8

Source: www.scribd.com/doc/19047168/19-Misleading-Graphs Irregular Scale Axes Source: www.scribd.com/doc/19047168/19-Misleading-Graphs 1993, 1996 and 1998 are added. End of Show 9