This document provides guidance on effectively communicating numerical information in news articles. It discusses best practices such as using consistency, providing context, presenting complete information, taking care with numbers, and making conversions between units. Specific tips include estimating before calculating, putting large numbers in perspective for readers, and clearly explaining percentage increases and decreases using starting amounts and differences. The goal is to help readers easily understand and interpret important numbers.

1. Newspaper math
Taking the numb out of numbers
by Joe Grimm
Michigan State University

2. “Well, if I called
the wrong number,
why did you
answer the phone?”
-- James Thurber

3. Crunch or be crunched
(don’t just sit there)
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Consistency
Context
Completeness
Care
Conversions

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. 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. 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. 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. Completeness
(Raw numbers AND processed)
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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. 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. Conversions
• Start by estimating
– Weight of a premature baby
– Boiling water
– The distance from Detroit to Chicago
• Then use conversion tables and calculators

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. 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. 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. 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. Do some on your own
(Estimate, calculate, think)
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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. 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. 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. 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. 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. 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?)