Does 2 + 2 = 5?

1. Does 2 + 2 = 5? The use of numbers to convince an audience is one of the most common techniques used. From using big numbers to scare an audience or poll numbers to convince a public, numbers are used all the time!

2. Raw Numbers vs. Percentages • Several children are abducted in 2003. The media makes it sound like an epidemic. Parents are searching online for tracking devices to be implanted on their children. The media uses raw numbers to show the numbers of children abducted: 15 in the past month in the U.S.

3. Raw Numbers vs. Percentages • Instead, statisticians can tell you that the chance of a child being abducted is 1 in one million. • How can both be true? 15/15,000,000 = 1 in one million

4. Raw Numbers vs. Percentages • Mosh Pit Deaths: • 24 killed in mosh pits in the year 2001. • Percentage of those in mosh pits that get killed? 24/? = %

5. Median vs. Mean • What is the Mean? It is the average of all numbers in a list. • What is the Median? It is the middle number when all the numbers are arranged sequentially from high to low.

6. Median vs. Mean • If you heard on the news these two facts, which is true? • In 1998 the mean annual income for retired families was $32,600. • In 1998 the median annual income for retired families was $19,300.

7. Median vs. Mean Both are true! 0 0 0 0 0 0 15,000 15,000 15,000 30,000 60,000 90,000 +500,000 /32,600 = AVERAGE 0 0 0 0 5,000 10,000 19,300 19,300 19,500 19,600 30,000 60,000 90,000 +500,000 MEDIAN MEAN

8. Unadjusted vs. Adjusted Numbers • Your boss gives you the good news. When you get transferred to San Francisco from Waco, you’ll get a big raise of $1.00/hour. • You discover that your grandparents bought their very first house for only $5,000. That house must have been a dump!

9. Unadjusted vs. Adjusted Numbers • Be sure that you’re comparing “apples to apples.” • Ask yourself: What is the cost of living in San Francisco compared to Waco? • Ask yourself: What was the average income of a family when your grandparents bought their first home?

10. Unadjusted vs. Adjusted Numbers • The authors of the website End Sweatshops Now tell you that workers in Pakistani sweatshops work in the heat on dirt floors and make only $1.00/day. BUT • Nicolas Kristoff in “Let them Sweat” told you that workers in Pakistan outside of the sweatshops work in the bright sunlight in the dirt and garbage around dead carcasses making $.30/day.

11. Base Point for Statistical Numbers • In the summer of 2002, the stock market was in precipitous decline if one compared 2002 prices with 2000 prices.

12. Base Point for Statistical Numbers • However, the market was still vigorous and healthy if one compared 2002 with 1990

13. Your Turn A proposal to build a new ballpark in Seattle, Washington, yielded a wide range of statistical arguments. All of the following statements are reasonably faithful to the same facts.

14. Pick Your Evidence in Support of the Ballpark • The ballpark would be paid for by raising the sales tax from 8.2 percent to 8.3 percent during a 20-year period. • The sales tax increase is one-tenth of 1 percent. • This increase represents an average of $7.50 per person per year---about the price of a movie ticket.

15. Pick Your Evidence Against the Ballpark • This tax increase represents $750 per five-person family over the twenty-year period of the tax. • For a family building a new home in the Seattle area, this tax will increase building costs by $200. • This is a $250 million tax increase for the residents of the Seattle area.