1. Chapter 1.5 – The Media Mathematics of Data Management (Nelson) MDM 4U
The Power of Data
Chapter 1.5 – The Media
Mathematics of Data Management (Nelson)
MDM 4U
There are 3 kinds of lies: lies, damn lies and statistics.

2. Example 1 – Changing the scale on the axis
What do you notice about the following bar graphs?

3. Example 1 – Scale from 0
Consider that this is a bar graph – could it still be misleading?

4. Include every category!

5. Example 2 – Using a Small Sample
What is the smallest possible sample size for 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) 
“Did you know that 1 in 4 women can misread a traditional pregnancy test result?” (Clearblue Easy Digital Pregnancy Test)
“Using Pedigree® DentaStix® daily can reduce the build up of tartar by up to 80%.”

6. Details on the Trident Survey
How many dentists did they ask?
Actual number: 1200
4 out of 5 is convincing but reasonable
5 out of 5 is preposterous
3 out of 5 is good but not great
Actual statistic 85%
Recommend Trident over what?
There were 2 other options:
Chewing sugared gum
Not chewing gum

7. Misleading Statements(?)
How could these statements be misleading?
“More people stay with Bell Mobility than any other provider.”
“Every minute of every hour of every business day, someone comes back to Bell.”
60 x 60 x 7 x 5 =

8. 2) How could the data be used to arrive at this conclusion falsely?
Does not specify how many more customers stay with Bell.
e.g. Percentage of customers renewing their plan:
Bell: 30% Rogers: 29% Telus: 25% Fido: 28%
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?
Competitors’ renewal rates may have decreased due to family plans / bundling
Does the data include Private / Corporate plans?

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

10. MSIP / Homework
Read pp. 57 – 60 Ex. 1-2
p. 60 #1-6