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# Math for journalists, or Numbers in the News

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This lecture goes over the way journalists should handle numbers in news copy. Simple math is all it takes for most journalism, but journalists need to be consistent, offer context, be complete, take care that the numbers are right and estimate before converting. Numbers in the news is one area where journalists can especially offer the benefit of critical thinking. Includes lessons on calculating percentage.

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### Math for journalists, or Numbers in the News

1. 1. Newspaper math Taking the numb out of numbers by Joe Grimm Michigan State University
2. 2. “Well, if I called the wrong number, why did you answer the phone?” -- James Thurber
3. 3. Crunch or be crunched (don’t just sit there) • • • • • Consistency Context Completeness Care Conversions
4. 4. Consistency John Smith, who survived World War II and the Korean conflict, died of an accidental gunshot wound Thursday. He was 67. Smith was survived by five sons: John Jr., George, Mark and Williams, and a daughter, Berry Lords.
5. 5. Context (know your numbers) Detroit population Michigan population U.S. population 700,000 10 million 313 million Comerica Park Ford pre-tax earning Michigan budget, 2014 U.S. spending budget ’14 \$200-\$300 million \$8.6 billion \$35 billion \$3.77 trillion
6. 6. Context II: Make it meaningful “The value of (Gates’) stock … reached an incredible \$81.4 billion. To put that in perspective: That’s 209,357,326 14-ounce tins of Beluga caviar or 513 Boeing 747s, or nearly the gross domestic product of Israel. In other words, it’s a lot more money than most people can fathom.” -- USA Today
7. 7. Thrill of a trill ... Say you had the chance to blow about \$2 trillion. You could: • Buy 43,478,260 Jaguar XF convertibles – more than four for everyone in Michigan. • Pay off credit card debt for EVERYONE in the United States -- four times! • Give \$6,389 to each of the 313 million people in the United States.
8. 8. Completeness (Raw numbers AND processed) • • • • • • A 7 percent increase in MSU’s budget Putting 1,000 more police on U.S. streets One million workers wear headphones Sanitation workers get a 10 percent raise The hospital cut 200 workers Auto Show attendance is up 12 percent
9. 9. Use care • Does it make sense? • Is it million or billion? • Is that an increase of 2 percent, or 2 percentage points? • Watch superlatives • Check dates, phone numbers
10. 10. Conversions • Start by estimating – Weight of a premature baby – Boiling water – The distance from Detroit to Chicago • Then use conversion tables and calculators
11. 11. Meet the average Joes Jo: 45; Joe: 40; Bill, 11; Peg & Pete, 7 • Average age: 22 • Median age: 11 • Mode: 7 What does this imply about the average wage at Microsoft?
12. 12. Percentage • Percent simply means “per hundred.” • That means a percent can be expressed as anything divided by a hundred. • We generally don’t have trouble with a percentage: “27 percent of students have tattoos.” • The difficulty is with percent change
13. 13. Percent increase • Three numbers are under consideration: – What you start with – What you end with – The difference • Any two will give you the third and the percentage
14. 14. Let’s try one • What is the percent increase from 50 to 75? – The difference is 25. – Divide the difference by the starting number: 25/50 = .5 = 50% Answer: A 50 percent increase
15. 15. Do some on your own (Estimate, calculate, think) • • • • • • What is the increase: from 100 to 200? From 40 to 65? From 2,800 to 35,000? From \$9.47 to \$12.13? From \$1.4 million to \$1.9 million?
16. 16. Percentage decrease • We still are focusing on the difference between before and after. • We still divide the difference, or the amount of the change, by the starting number. • The only thing that changes is we are starting with a larger number, rather than a smaller number.
17. 17. Let’s try a decrease together • What is the percent decrease from 75 to 50? – The difference is 25. – Divide the difference by the starting number: 25/75 = .33 = 33% Answer: A 33 percent decrease (Why wasn’t the answer 50% this time?)
18. 18. This time, you know the percent • Calculating percentage changes is easy. Simply multiply the beginning number by the percentage. • Remember, NO increase would be times 1, so a 20 percent increase would mean you multiply the starting number by 1.20.
19. 19. Try some increases • What would a 20 percent increase do to a \$800 paycheck? • A city with a population of 70,000 grows by 7 percent • A state budget of \$185,000 goes up by 30 percent.
20. 20. Now, try some decreases • What would a 20 percent decrease do to a \$800 paycheck? • A city with a population of 70,000 shrinks by 7 percent • A state budget of \$185,000 goes down by 30 percent. (What about the numbers this time? Why?)