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##### Presentation Transcript

1. Misleading Graphs and Statistics Chapter 2

2. Questions to Ask When Looking at Data and/or Graphs • Is the information presented correctly? • Is the graph trying to influence you? • Does the scale use a regular interval? • What impression is the graph giving you?

3. Why is this graph misleading? This title tells the reader what to think (that there are huge increases in price). The scale moves from 0 to 80,000 in the same amount of space as 80,000 to 81,000. The actual increase in price is 2,000 pounds, which is less than a 3% increase. The graph shows the second bar as being 3 times the size of the first bar, which implies a 300% increase in price.

4. A more accurate graph: An unbiased title A scale with a regular interval. This shows a more accurate picture of the increase.

5. Why is this graph misleading? The scale does not have a regular interval.

6. Graphs can be misleading in the news. • The margin of error is the amount (usually in percentage points) that the results can be “off by.” • Be wary of data with large margins of error.

7. From CNN.com

8. Problems: • The difference in percentage points between Democrats and Republicans (and between Democrats and Independents) is 8% (62 – 54). Since the margin of error is 7%, it is likely that there is even less of a difference. • The graph implies that the Democrats were 8 times more likely to agree with the decision. In truth, they were only slightly more likely to agree with the decision. • The graph does not accurately demonstrate that a majority of all groups interviewed agreed with the decision.