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Misleading Graphs and StatisticsPowerPoint Presentation

Misleading Graphs and Statistics

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Misleading Graphs and Statistics

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Misleading Graphs and Statistics

MEAP REVIEW

- 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?

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.

An unbiased title

A scale with a regular interval.

This shows a more accurate picture of the increase.

The scale does not have a regular interval.

- 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.

- 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?

- 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.

- 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.