Misleading Graphs

Image Source: http://www2.fiu.edu

Graphs are often deliberately made misleading when put on TV or in Newspapers.

The graph shown below is designed to make it look like after a small drop in unemployment, it started to go up and get much worse under the Obama presidency.

Image Source: http://cloudfront.mediamatters.org

The graph has been made misleading by not starting the vertical scale at zero, and by using very detailed values that contain one decimal place on the scale.

If the scale had been made in units of 0.5, instead of 0.1, the employment situation would look very flat and not changing much, which is in fact the real case.

Also note that the 8.6 value for November on the far right side of the graph has not been plotted correctly, and is placed at a value of 9.0.

Misleading graphs give people the wrong idea about what is really going on.

They are often used by Advertisers and the Media.

Ways to Make a Graph Misleading

Vertical scale is too big or too small.
Vertical axis skips numbers, or does not start at zero.
Graph is not labeled properly.
Graph does not have a Title to explain what it is about.
Data is left out.
Scale not starting at zero.
Scale made in very small units 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.

Videos About Misleading Graphs

[youtube http://www.youtube.com/watch?v=ETbc8GIhfHo]

 
 

Here is another video that explains the common types of Misleading Graphs.

[youtube http://www.youtube.com/watch?v=wSCjtHt9qAU]

 
 

Let’s now look at some examples of the common types of Misleading Graphs.

Scale Not Starting at Zero

Here is another American Unemployment graph that has made a tiny difference look huge by using small scale units, and drawing the bars in 3D.

In this next graph, the bowling average difference between Emily and Diana is only 5, but is made to look much larger.

This next graph makes it look like there were twice as many freezing days in the USA in 2008 compared to 2007, when there were in fact only two extra freezing days in 2007.

This next graph makes the House Prices in 2006 look huge compared to 1975.

Also the next year after 1995 on the horizontal scale should in fact be 2005, and not 2006.

Misleading Picture Graphs

In Picture Graphs, (also called “Pictographs”), all of the image icons used to represent the different items should be made the same size.

By making these items different sizes, we can try and trick people who are looking at the Graph.

In the graph shown below, the Dogs have been drawn much bigger that the Cats, to make it look like there are more dogs.

However, if we count the icons, there are actually only 5 dogs compared to 7 cats.

Oversized Volumes on Graphs

In these type of graphs, images are used to replace normal vertical bars, and some of the volumes or sizes of these images are made much bigger than they should be.

Here is another misleading graph, where the volume of the second image is about one and a half times bigger than it should really be.

Incorrect Pie Charts

In these graphs, the pieces of pie sections are made the wrong size.

In the graph below, the right hand side pieces add up to 145 million, which is not equal to the 250 million piece on the left hand side.

Also the 10% piece has been made way too big.

Non Standard Graphs Used

Here is another non-standard type of graph that is very hard to understand

Fake Graphs Created

We doubt seriously whether the statistics in the following graph are true.

Image Source: http://mathspig.files.wordpress.com

Misleading Graphs Summary

The following is a summary of what to look out for when identifying Misleading Graphs.

Related Items

Basic Histogram Graphs
Grouped Data Histograms Using Class Intervals
MS Excel Charts and Graphs
MS Excel Column Graphs and Pie Charts
Funny Graphs from Graph Jam
Real World Line Graphs
Averages – Mean Median Mode (including MS Excel)
Free Online Graph Makers
Stem and Leaf Plots (Stem Plots)
Real World Charts and Graphs

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