# Misleading graphs

### learn about them today

## why are misleadiong graphs made??

Misleading graphs may be created intentionally to hinder the proper interpretation of data or accidentally due to unfamiliarity with graphing software, misinterpretation of data, or because data cannot be accurately conveyed. Misleading graphs are often used in false advertising. One of the first authors to write about misleading graphs was Darrell Huff, publisher of the 1954 book How to Lie with Statistics.

## examples of misleading graphs

## example 1 From this graph it looks as though house prices have trebled in one year! It is misleading because the vertical axis does not start at 0. Look at the 'improved' version of the same graph. This gives a much more accurate picture of what has happened. | ## example 2 Although the vertical scale starts at 0, it does not go up in even steps. This has the effect of distorting the graph, and making it look as though the biggest jump is between 1 and 2 rather than 3 and 4. Also, there are no labels on the axes. We have no idea what this graph represents! | ## example 3 This 3D bar chart might look very attractive, but it is also very misleading. There is no scale on the vertical axis, and because of the perspective it looks as though the sales for 1995 were far greater than those for any other year. In fact they were identical to those for 1997. It would be much better to draw a 2D bar chart. |

## example 1

From this graph it looks as though house prices have trebled in one year! It is misleading because the vertical axis does not start at 0. Look at the 'improved' version of the same graph. This gives a much more accurate picture of what has happened.

## example 2

Although the vertical scale starts at 0, it does not go up in even steps. This has the effect of distorting the graph, and making it look as though the biggest jump is between 1 and 2 rather than 3 and 4. Also, there are no labels on the axes. We have no idea what this graph represents!

## example 3

This 3D bar chart might look very attractive, but it is also very misleading. There is no scale on the vertical axis, and because of the perspective it looks as though the sales for 1995 were far greater than those for any other year. In fact they were identical to those for 1997. It would be much better to draw a 2D bar chart.

## how to aviod misleading graphs

The field of data visualization describes ways to present information that avoids creating misleading graphs.The following things are important to consider when looking at a graph: 1. Title 2. Labels on both axes of a line or bar chart and on all sections of a pie chart 3. Source of the data 4. Key to a pictograph 5. Uniform size of a symbol in a pictograph 6. Scale: Does it start with zero? If not, is there a break shown 7. Scale: Are the numbers equally spaced?