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# Misleading Graphs and Statistics - PowerPoint PPT Presentation

Misleading Graphs and Statistics. MEAP REVIEW. 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?.

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Presentation Transcript

MEAP REVIEW

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?

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.

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?

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.