MISLEADING GRAPHS:Can they fool you?

Powerpoint by Student

Here’s how to detect a misleading graph:

1. If the scale is too narrow or there is not a big enough range. Data looks like it has a big difference really does not.

2. If there is no scale at all. 3. If the bars are not equal widths. 4. If the intervals on the graph are not

equal, but are depicted as equal. 5. Graphs can also be misleading if there is

missing information. 6. If it’s a pictogram, then all of the

pictured items may not be the same size.

Learning Objectives

• You will be able to identify whether graphs are misleading. 

• You will be able to identify the factors that can make bar graphs, line graphs, and scatter plots misleading. 

• You will be able to interpret whose interests are favored by misleading graphs. 

Think About It:

• What is misleading about this graph?

• How could the graph be changed to reflect the data more accurately?

• Why would someone make a graph that is misleading in this way?

Why is this graph misleading?

The same data:

www.mediamatters.org/items/200503220005

THE SAME DATA!

Other factors that make a graph misleading:

• Y-axis scale is too big or too small• Y-axis skips numbers, or does not start at zero

• X-axis scale is too big or too small• X-axis skips numbers, or does not start at zero

• Axes are not labeled• Data is left out• What else?

Think Pair Share

• What is misleading about this graph?

• How could the graph be changed to reflect the data more accurately?

• Why would someone make a graph that is misleading in this way?

• http://sde.state.ok.us/publ/invest00/bench.html

• http://www.brickonomist.net/?cat=20

Activity Time

• Gather class data on a topic of your choice

• Research to find graphs on your topic

• Make a class data table• Individually graph it:

– Accurate graph– Misleading graph

Presentation Time!

• Now that you’ve researched and designed your own accurate and misleading graph, show and tell what you’ve learned about graphs and how they can be skewed so that the viewer sees what is wanted rather then what is actual.

• Share with your tablemates

Resources• http://mathforum.org • syssci.atu.edu/math/faculty/finan/2043/section31.pdf

• www.ms.uky.edu/algebracubed/lessons/Graphs.pdf