Information about Math 4 Journalists

Journalists can brush up on basic math skills. This is important because many stories involve numbers.

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“ If I wanted to do math, I wouldn’t have majored in journalism!” As a journalism professor, I hear this often. Most journalists would rather craft words than crunch numbers. But many stories require numbers. There are news stories about salaries, budgets, test scores, surveys, political polls, census data, etc. And nearly all sports stories involve numbers. So not only do journalists need to be good writers, they also need some math skills. This slideshow tutorial will cover the basics. Mark Grabowski Journalism Professor Marist College

As a journalism professor, I hear this often. Most journalists would rather craft words than crunch numbers. But many stories require numbers. There are news stories about salaries, budgets, test scores, surveys, political polls, census data, etc. And nearly all sports stories involve numbers. So not only do journalists need to be good writers, they also need some math skills. This slideshow tutorial will cover the basics.

Percentage change Use this formula: (New – Old) /Old … then x 100 For example: Last year’s ticket sales brought in $1,000. This year’s ticket sales brought in $1,250. What was the percentage change? 1250-1000 = 250 250/1000 = .25 .25 x 100 = 25%

Use this formula:

(New – Old) /Old … then x 100

For example: Last year’s ticket sales brought in $1,000. This year’s ticket sales brought in $1,250. What was the percentage change?

1250-1000 = 250

250/1000 = .25

.25 x 100 = 25%

Percentage change The International Club’s budget was cut last year from $2,000 to $1,000. What was the percentage change? 1000 – 2000 = - 1000 -1000/2000 = -.5 -.5 x 100 = - 50%

The International Club’s budget was cut last year from $2,000 to $1,000. What was the percentage change?

1000 – 2000 = - 1000

-1000/2000 = -.5

-.5 x 100 = - 50%

Percentage change Last year, the city had 3 homicides. This year there were 0. What was the percentage change? 0-3 = - 3 -3/3= - 1 -1 x 100 = - 100%

Last year, the city had 3 homicides.

This year there were 0.

What was the percentage change?

0-3 = - 3

-3/3= - 1

-1 x 100 = - 100%

Percentage change Last year’s sorority budget was $12,000. This year, there will be a 10% cut. Next year, there will be a 10% increase. What will the new budget be this year? Will we be back to normal NEXT year?

Last year’s sorority budget was $12,000.

This year, there will be a 10% cut.

Next year, there will be a 10% increase.

What will the new budget be this year?

Will we be back to normal NEXT year?

Percentage change A 10% decrease is a change of -.10 12000 x - .10 = - 1200 12000 – 1200 = 10,800 this year A 10% increase is a change of +.10 10800 x .10 = 1080 10800 + 1080 = 11,880 next year

A 10% decrease is a change of -.10

12000 x - .10 = - 1200

12000 – 1200 = 10,800 this year

A 10% increase is a change of +.10

10800 x .10 = 1080

10800 + 1080 = 11,880 next year

Percentage change Be careful! A 200 percent increase is not the same as “double.” It’s a 100 percent increase that is actually the figure that is twice the size of the previous number. A 200 percent increase is triple the original.

Be careful! A 200 percent increase is not the same as “double.” It’s a 100 percent increase that is actually the figure that is twice the size of the previous number. A 200 percent increase is triple the original.

Rate per thousands … When calculating percent, we multiply by 100 because that’s what percent means: per 100. If calculating a rate per 1,000 people or per 10,000 people, we multiply by THAT number.

When calculating percent, we multiply by 100 because that’s what percent means: per 100.

If calculating a rate per 1,000 people or per 10,000 people, we multiply by THAT number.

Rate per thousands Your city of 350,000 had 70 murders last year. What was the murder rate per 100,000? 70/350,000 = .0002 .0002 x 100,000 = 20 This way different cities’ rates can be compared.

Your city of 350,000 had 70 murders last year. What was the murder rate per 100,000?

70/350,000 = .0002

.0002 x 100,000 = 20

This way different cities’ rates can be compared.

Crowd counts Handy rule: In a loose crowd, each person takes up about 10 square feet. How many people are at a protest demonstration that loosely fills a city square that measures 50 yards on each side? 50 yards = 150 feet. 150 x 150 = 22,500 square feet 22,500/10 = 2,250 protesters

Handy rule: In a loose crowd, each person takes up about 10 square feet.

How many people are at a protest demonstration that loosely fills a city square that measures 50 yards on each side?

50 yards = 150 feet.

150 x 150 = 22,500 square feet

22,500/10 = 2,250 protesters

Crowd counts Handy rule: In a tight crowd, each person takes up about 7.5 square feet. The basketball team came home to a cheering crowd in an airport space about 75 x 20 feet. How many were there? 75 x 20 = 1500 square feet. 1500 / 7.5 = 200 people cheering

Handy rule: In a tight crowd, each person takes up about 7.5 square feet.

The basketball team came home to a cheering crowd in an airport space about 75 x 20 feet. How many were there?

75 x 20 = 1500 square feet.

1500 / 7.5 = 200 people cheering

Mean v. Median A mean is an average . If your quiz scores are … 9, 8, 6, 8, 4 … then your average is (9 + 8 + 6 + 8 + 4)/5 = 7

A mean is an average .

If your quiz scores are …

9, 8, 6, 8, 4

… then your average is

(9 + 8 + 6 + 8 + 4)/5 = 7

Mean v. Median A median is a midpoint. Your median quiz score would be … 9 8 8 6 4

A median is a midpoint.

Your median quiz score would be …

9

8

8

6

4

Mean v. Median This difference can be important in news stories. “The average salary of a Marist College graduate in Public Relations is $100,000.” … true statement!

This difference can be important in news stories.

“The average salary of a Marist College graduate in Public Relations is $100,000.”

… true statement!

Mean v. Median The explanation goes something like this: Anjali Agarwal $ 10,000 Ben Billman 20,000 Cathy Clark 22,500 Dave Dawson 25,000 Rick Smits 422,500 $500,000 500,000/5 = $100,000 each! … But what’s the median ?

The explanation goes something like this:

Anjali Agarwal $ 10,000

Ben Billman 20,000

Cathy Clark 22,500

Dave Dawson 25,000

Rick Smits 422,500

$500,000

500,000/5 = $100,000 each!

… But what’s the median ?

Rounding numbers It’s OK to round off large numbers in your stories. For example, you can use 1.4 million instead of 1,421,317. But be careful rounding to just two digits – rounding 1,562,000 up to 1.6 million leaves out almost 40,000 of whatever. That’s a pretty significant amount. So, it may be more accurate to round down to 1.56 million

It’s OK to round off large numbers in your stories. For example, you can use 1.4 million instead of 1,421,317. But be careful rounding to just two digits – rounding 1,562,000 up to 1.6 million leaves out almost 40,000 of whatever. That’s a pretty significant amount. So, it may be more accurate to round down to 1.56 million

How to Write Numbers The AP Stylebook ’s general rule is to spell out numbers from zero through nine and use numerals for numbers 10 and above. If it has two digits or more, make it a number! Some exceptions are millions, percentages, ages, years, headlines – always use numbers for these. Note that you spell out “percent,” “feet,” “inches,” “yards,” etc. in stories. There are references to numbers throughout the AP Stylebook , but many of the commonly-used figures are under the ‘dimensions’ entry.

The AP Stylebook ’s general rule is to spell out numbers from zero through nine and use numerals for numbers 10 and above. If it has two digits or more, make it a number!

Some exceptions are millions, percentages, ages, years, headlines – always use numbers for these.

Note that you spell out “percent,” “feet,” “inches,” “yards,” etc. in stories.

There are references to numbers throughout the AP Stylebook , but many of the commonly-used figures are under the ‘dimensions’ entry.

For more tips and practice… Visit http://CubReporters.org/math E-mail mark@cubreporters.org Questions?

Visit http://CubReporters.org/math

E-mail mark@cubreporters.org

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