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.

Example 1 – Changing the scale on the axis What do you notice about the following bar

graphs?

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Example 1 – Scale from 0

Consider that this is a bar graph – could it still be misleading?

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Include every category!

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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%.”

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

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 = 126 000

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?

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

MSIP / Homework

Read pp. 57 – 60 Ex. 1-2 p. 60 #1-6