Manipulation with charts – illusion in digital era

People like charts. They become a standard in presentations and business communication. Stats, charts, numbers are perceived as very strong rational arguments. But statistics and charts can be easily used to manipulate and mislead people as well. To support a false thesis or to hide the facts. I can show you some of techniques used in manipulation.

The perspective trick

Manipulative chart (source: Engagdet)

We begin with a trick used even by famous people.

If you look at the picture you will see a green area which looks rather big. It looks significantly bigger than the violet area.

But look at the numbers: violet (21,2%) and green only 19,5%!

The man in the picture is Steve Jobs (RIP) and he is presenting the market share of different operation systems. Yes, green represents Apple.

It is working just because the perspective was used intentionally. The smaller green area is closer so it looks bigger than the violet one which is bigger, but further – so it looks smaller. Like a picture of a hotel pool taken by a travel agency – always looks bigger than in reality.

This picture of Steve Jobs (RIP) was taken in 2008 and published in Engadget.

Scaling trick

This one is very common. I think that newspapers and television use it everyday.

Imagine that the charts below illustrate how the members of two political parties support a controversial law act in the Parliament.

The chart with scale manipulation

The chart with scale manipulation

In case of both political parties the reality is that more or less half of the party members support the controversial act. 52% or 56% is not a significant difference.

But when you display it using the y-scale of 50-57% then the difference seems rather big (left chart). The same data charted with y-scale beginning from 0 shows a different image. Great stuff for political marketers.

The same data – different charts – different perception of reality.

Choose the right unit

Both charts below illustrate military spendings.

Military spending (found on SunBin blog, ilustrated by Economist)

First chart shows spendings in absolute, raw values. China looks like an aggressive nation. The next one shows the same spendings but expressed as a percentage of GDP. Who seems more agressive?

The second question that comes to my mind, is what is going on with the US GDP?

The same data – different charts – different perception of reality.

Grouping

The next trick is grouping data in categories to get the desired shape of a chart.

Look at those charts. In the first chart you can see that the highest taxable income is in the middle class category (100-200K). The right chart shows that the “richest” have the highest income.

Taxes in USA chart (found on motherjones.com)

Choose the chart which represents your political believes. Both are true and based on the same data – just different categorization.

The same data – different charts – different perception of reality.

The charts were found on motherjones.com.

Trend hiding (advanced)

Sometimes one has to hide the real trend. Imagine that you have to present  the sales results of last year to the management. But your favorite product Beta has a negative trend with 10% of revenue fall and other products (which you do not like so much) have a good, positive trend. The data is presented below.

Do not panic – just use the stacked bar chart and everything is going to be all right.

Hiding trend of Beta 10% fall

Do you see that Beta (red) trend is negative?

Not really – the Alfa bars make the Beta bars go higher. Using narrow bars makes it harder to notice.

But wait – your “collegue” who hates Beta shows her chart of the same data.

The trend is very impressive

See the difference?

The same data – different charts – different perception of reality.

Summary

I do not want to convince anyone to manipulate perception of the data with chart tricks. However it is worth to know how it works in order to not be manipulated.

The statistic science does not lie. But the statistical stuff can be used to change the perception of facts.

It is used by illusionist of the 21st century. You see what I want you to see and you believe me, because I show you real numbers.

Related Post

← Previous post

Next post →

Leave a Reply