Deceptive Graph Techniques: How to identify misleading graphs
When they’re used well, graphs can help us intuitively grasp complex data. But as visual software has enabled more usage of graphs throughout all media, it has also made them easier to use in a careless or dishonest way — and as it turns out, there are plenty of ways graphs can mislead and outright manipulate.
Front Porch Math’s developer, Lea Gaslowitz, helped create this video for Ted-Ed.
Misleading Graphs pt. 2, in this talk we look at how circle, 3-D, picture, and double line graphs can be misleading. By examining real graphs we look at how the design can effect how we understand the data.
Let’s analyze an example
At the end of this page is a list of common ways graphs can be manipulated to mislead us and shape our opinions. But before looking at the list lets examine one misleading graph in detail.
When looking at this graph, ask following questions:
Is the scale is distorted?
Was there any reason that the graph did not start a zero?
Did you notice that the last entry 8.6% is at the same height as 9.0%
What happened to December?
Is 0.6% difference in unemployment significant?
Using the same data I could create a graph that told a very different story:
But this graph is also misleading.
Look at the y-axis.
By making the scale very small, I have made small changes look bigger.
First let’s redraw the graph starting at zero. Notice that there seems to be a slight downward trend.
Still there are more questions we might want to ask.
Was the data “cherry picked?
Why are we only looking at one year?
By leaving out data, making the scale very small, and not starting at zero the impression that the graph leaves is very different.
Still we need to ask ourselves, do we have all the information we need? What is the normal unemployment rate? What led to the higher unemployment rate?
Lets look a graph that covers from 2007-2016.
Further Information needed:
The heading in the original graph was “Unemployment Rate under President Obama.” This title is designed to influence your interpretation of the cause of the higher unemployment rate, but could it be misleading. Was President Obama responsible for the high unemployment rate, or was it part of subprime mortgage crisis? The subprime mortgage crisis (hi-lighted in yellow) created a nationwide banking emergency that contributed to the U.S. recession of December 2007 – June 2009.
Deceptive Graph Techniques:
1. Graph is accurate, but misleading
a. giving an irrelevant correlation
b. ignoring other variables
examples: asking the wrong questions
not factoring in population growth
missing information to needed to understand the data
c. “cherry picking” data
d. graph is not properly labeled
2. Scale is distorted
a. scale does not start at zero
b. scale is enlarged
c. scale is too small
d. there is no scale or units are missing
3. Graph is not accurately drawn or distorts the information
a. pieces of the graph appear larger or smaller than they should
ex. 3-D graphs
ex. picture graphs
b. percents don’t add up to 100
c. pieces in a chart are not in the correct ratios
d. graph is drawn upside down
e. units are not evenly or proportionally spaced
The “NOTE” section contain 24 examples of misleading graphs.
Educators — the “Teacher” section includes lesson plans and a detail analysis of the 24 graphs along with examples of how some of them would look if they were not misleading. (You will need to sign in to get this section.)