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.

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

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

Include every category!

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