Misleading Graphs and Statistics

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## Misleading Graphs and Statistics

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**Misleading Graphs and Statistics**Chapter 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?**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.**A more accurate graph:**An unbiased title A scale with a regular interval. This shows a more accurate picture of the increase.**Why is this graph misleading?**The scale does not have a regular interval.**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.**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.**What does the top of this graph show?**• About 12 million people are downloading music legally. • Just over 9 million people are downloading music illegally. The bottom of the graph is misleading. Why? • The graph implies that 1% of the iPods are filled with legally downloaded music. • It implies that the other 99% are filled with illegally downloaded music. Why is this wrong?**What could be in those iPods besides legally downloaded**music? • Empty space – most people don’t have iPods that are filled to capacity. • Songs that were added from legally purchased CDs. • Games, calendars, other applications. • Songs that were downloaded illegally. It is possible that the rest of the iPod contains some illegally downloaded music, but it is unlikely that 99% of a person’s iPod is filled with illegal music.**More information:**• The iPod graphic appeared in Wired magazine. • A quote from the article: “What’s filling all that excess capacity? Well, despite the efforts of the Recording Industry Association of America, nearly a billion songs are traded on P2P networks every month.” • This article was trying to imply that all of the excess space is filled with illegal downloads, which is likely untrue. • The statistics for the article were provided by the music industry.