1. 1.5: The Power of Data - The Media
There are 3 kinds of lies: lies, damn lies and statistics.

2. Example 1 – Changing the scale on the vertical axis
Why is the following graph misleading?
The fact that the scale on the vertical axis does not start at 0 makes it misleading. Ms. Meleta’s bar looks many times bigger than all the others, though it is really only bigger by a few votes.

3. Example 1 – Re-scaled But… Could this bar graph still be misleading?
Make sure all the data has been included (along the horizontal axis, in particular)…

4. Example 1 – Where every category is included (sorry Ms. Yearwood!)

5. And one more thing... 3-D graphs are a fun idea, but they are hard to read and therefore confusing.

6. Example 2 – Using a Small Sample
What type of bias will this likely create?
Sampling bias! (Where the sample does not properly represent the population.)
What is the smallest possible sample size, given each of the following statements?
“4 out of 5 dentists recommend Trident sugarless gum to their patients who chew gum.”
“In the past, we found errors in 4 out of 5 of the returns people brought in for a Second Look review.” (H&R Block)
“Using Pedigree® DentaStix® daily can reduce the build up of tartar by up to 80%.”

7. Details on the Trident Survey
How many dentists did they ask?
1200
4 out of 5 is both convincing and reasonable
5 out of 5 would be preposterous (unbelievable)
3 out of 5 is good but not great
The actual statistic was 85%
Recommend Trident over what?
There were 2 other options: chewing sugared gum or not chewing gum at all

8. Examples of Misleading Statements
Statement #1: “More people stay with Bell Mobility than any other provider.”
Statement #2: “Shopping at Save-a-Lot can save you up to $100 a month!”

9. How could the data be used to arrive at those conclusions falsely?
Statement #1:
Does not specify how many more customers stay with Bell.
Did they compare percentages or totals?
What does it mean to “stay with Bell”? Honour entire contract? Renew contract at the end of a term?
Are early terminations factored in? If so, does Bell have a higher cost for early terminations?
Does the data include Private or Corporate plans, or both?

10. Statement #2:
The words “save up to $100” mean that the maximum you can save is $100, but there is no guarantee that you will save that amount!

11. How does the media use (misuse) data?
To inform the public about world events in an objective manner
To sometimes give misleading or false impressions to sway the public or increase ratings
It is important to:
Study statistics to understand how information is represented/misrepresented
Correctly interpret tables/charts presented by the media

12. Homework Read pp. 57 – 60 Ex. 1-2 p. 60 #1-6 Examples