Statistics can be manipulated in many ways that can be misleading. Graphs need to be carefully analysed and questions must always be asked about 'the story behind the figures.' Potential manipulations are:

- Changing the scale to change the appearence of a graph
- Omissions and biased selection of data
- Focus on particular research questions
- Selection of groups

** Investigation : Misuse of statistics **

- Examine the following graphs and comment on the effects of changing scale.
**Figure 1****Figure 2** - Examine the following three plots and comment on omission, selection and bias. Hint: What is wrong with the data and what is missing from the bar and pie charts?
Table 1 Activity Hours Sleep 8 Sports 2 School 7 Visit friend 1 Watch TV 2 Studying 3 **Figure 3****Figure 4**

** Misuse of Statistics **

The bar graph below shows the results of a study that looked at the cost of food compared to the income of a household in 1994.

Income (thousands of rands) | Food bill (thousands of rands) |

2 | |

5-10 | 2 |

10-15 | 4 |

15-20 | 4 |

20-30 | 8 |

30-40 | 6 |

40-50 | 10 |

12 |

- What is the dependent variable? Why?
- What conclusion can you make about this variable? Why? Does this make sense?
- What would happen if the graph was changed from food bill in thousands of rands to percentage of income?
- Construct this bar graph using a table. What conclusions can be drawn?
- Why do the two graphs differ despite showing the same information?
- What else is observed? Does this affect the fairness of the results?

Comments:"Accessible versions of this collection are available at Bookshare. DAISY and BRF provided. "