Friday, September 19, 2014
YOLO COUNTY NEWS
99 CENTS

‘Percent’ can be confusing

By
From page A6 | August 05, 2014 |

The letter by Mikal Saltveit published Friday, July 25, should have said that the increase in atmospheric carbon dioxide over the past 18 years is analogous to adding almost 7,000 people to the population of Davis, not 2.3 people. My hope in writing is to leave at least one person with a better understanding of math and climate change concerns.

If 6 ounces of beer in a glass is increased to 9 ounces, the result is 1.5 times the initial amount, the same as saying that half the initial amount was added. Such a change is widely referred to as a 50 percent increase while simultaneously being an extra 3 ounces.

If the number 0.06 is increased to 0.09, the extra 0.03 is similarly a 50 percent increase. If this same set of numbers is referred to as 6 percent changing to 9 percent, the increase is still 50 percent, while also being an extra 3 percent (trouble!). The latter might be stated as “3 percentage points” in an attempt to avoid the misinterpretation trap that caught the July 25 letter.

It is also misleading to think of “percent” as a substance like beer, or a unit of measure like ounces. The word “percent” means “divided by 100,” so 6 percent is exactly the same thing as 0.06.

“Percent” terminology makes ratios seem like adding and subtracting, a fallacy. A 50-percent increase followed by a 50-percent decrease does not lead back to the original number. Multiplying by 1.5, then taking away half of that result actually leads to three-quarters of the original number.

Carbon dioxide increased from 365 to 401 millionths of the atmosphere, simply 1.1 times as much, with no need to be confused by “percent.”

Math should not be treated as a toolbox of obscure procedures, analogous to speaking a foreign language from a phrase dictionary without practicing pronunciation and grammar. While we need words to communicate, math is not about words any more than French is about English, so reducing the usage of “percent” might be a key step toward fluency in math.

John Whitehead
Davis

Comments

comments

Letters to the Editor

.

News

Grant means new push for moving tracks out of town

By Dave Ryan | From Page: A1 | Gallery

 
Some say council needs to reconsider MRAP

By Dave Ryan | From Page: A1

UC to create $250 million venture capital fund

By San Francisco Chronicle | From Page: A1

 
School district may redevelop downtown site

By Jeff Hudson | From Page: A1

 
Master Gardeners share their wisdom at free workshops

By Enterprise staff | From Page: A2

Scots vote to stay in UK

By The Associated Press | From Page: A2

 
France strikes Islamic State group’s depot in Iraq

By The Associated Press | From Page: A2

Man faces arson charge in huge California wildfire

By The Associated Press | From Page: A2

 
DUI suspected in crash

By Lauren Keene | From Page: A2

Woodland Healthcare offering flu shots

By Enterprise staff | From Page: A3

 
Storyteller will draw on music, dance

By Enterprise staff | From Page: A3

 
Putah Creek Bike Path to close temporarily

By Enterprise staff | From Page: A3

Little Free Libraries open at Montgomery

By Anne Ternus-Bellamy | From Page: A3

 
Project Linus seeks donations

By Enterprise staff | From Page: A3

Rabid bat found at Holmes Junior High

By Enterprise staff | From Page: A3

 
Students invited to apply for Blue & White grants

By Enterprise staff | From Page: A3

Telling tales, on ‘Davisville’

By Enterprise staff | From Page: A3

 
Halloween costume sale benefits preschool

By Enterprise staff | From Page: A3

Volunteers sought to make veggie bags

By Enterprise staff | From Page: A3

 
Register to vote by Oct. 20

By Enterprise staff | From Page: A4

Free workout class set at library

By Special to The Enterprise | From Page: A4

 
Explorit: Lots of ways to be a volunteer

By Lisa Justice | From Page: A4 | Gallery

 
Sierra Club remembers longtime walker

By Special to The Enterprise | From Page: A4

DHS Classes of 1954 and 1955 will hold 60th reunion

By Enterprise staff | From Page: A4

 
Nonprofits can get DCN’s help

By Enterprise staff | From Page: A4

Davis maps available at Chamber office

By Enterprise staff | From Page: A5

 
Need a new best friend?

By Enterprise staff | From Page: A5 | Gallery

Reception benefits endangered gorillas

By Special to The Enterprise | From Page: A5

 
Downtown history tour planned in October

By Enterprise staff | From Page: A7

Wolk applauds approval of stronger rules for olive oil

By Special to The Enterprise | From Page: A8

 
Davis hosts its own climate change rally

By Special to The Enterprise | From Page: A8

Sutter Farmers Market offers local goods

By Enterprise staff | From Page: A8 | Gallery

 
Qigong classes available for heart health

By Enterprise staff | From Page: A9

.

Forum

Sick of being the bad guy

By Creators Syndicate | From Page: B5

 
Cheers and Jeers: Not the end of the rainbow

By Our View | From Page: A6

Tom Meyer cartoon

By Debbie Davis | From Page: A6

 
Return to previous plan

By Letters to the Editor | From Page: A6

Save the ‘pine cone place’

By Letters to the Editor | From Page: A6

 
Affirm our community values

By Letters to the Editor | From Page: A6

Project has safety risks

By Letters to the Editor | From Page: A6

 
Learn more about Paso Fino

By Letters to the Editor | From Page: A6

Educate homeless with dogs

By Letters to the Editor | From Page: A6, 1 Comment

 
.

Sports

Aggies’ new energy could be scary for Big West

By Bruce Gallaudet | From Page: B1

 
No rest for the weary: Aggie TE Martindale busy on and off the field

By Bruce Gallaudet | From Page: B1 | Gallery

Devils hope the light bulb turns on at Edison

By Enterprise staff | From Page: B1

 
River Cats and Giants sign two-year deal

By Enterprise staff | From Page: B1

Blue Devil volleyballers hold off Herd

By Spencer Ault | From Page: B1 | Gallery

 
Take Zona and Bama this week

By Bob Dunning | From Page: B2

Mustangs are no match for DHS boys in water polo

By Enterprise staff | From Page: B2

 
A’s slide continues as Rangers sweep

By The Associated Press | From Page: B8

.

Features

Name Droppers: Awards keep coming for UC Davis retiree

By Enterprise staff | From Page: A7

 
.

Business

Redesigned 2015 Escalade remains breed all its own

By Ann M. Job | From Page: B3 | Gallery

 
.

Obituaries

.

Comics

Comics: Friday, September 19, 2014

By Creator | From Page: A10

 
.

Real Estate Review

Featured Listing

By Zack Snow | From Page: RER1

Professional Services Directory

By Zack Snow | From Page: RER2

Taylor Morrison

By Zack Snow | From Page: RER3

Malek Baroody

By Zack Snow | From Page: RER4

Norcal Land

By Zack Snow | From Page: RER5

Robin Garland

By Zack Snow | From Page: RER6

Karen Waggoner

By Zack Snow | From Page: RER7

Dana Hawkins

By Zack Snow | From Page: RER7

Martha Bernauer

By Zack Snow | From Page: RER8

Joe Kaplan

By Zack Snow | From Page: RER8

Lynne Wegner

By Zack Snow | From Page: RER8

Remax

By Zack Snow | From Page: RER9

Melrina A Maggiora

By Zack Snow | From Page: RER10

Wells Fargo Home Mortgage

By Zack Snow | From Page: RER11

Julie Leonard

By Zack Snow | From Page: RER11

Coldwell Banker

By Zack Snow | From Page: RER12

Kim Eichorn

By Zack Snow | From Page: RER14

Lyon Real Estate

By Zack Snow | From Page: RER15

Julie Partain

By Zack Snow | From Page: RER16

Jamie Madison & Associates

By Zack Snow | From Page: RER16

Marcelo Campos

By Zack Snow | From Page: RER16

Bob Bockwinkel

By Zack Snow | From Page: RER17

Juan Ramirez

By Zack Snow | From Page: RER17

Kim Merrel Lamb

By Zack Snow | From Page: RER17

Chris Snow

By Zack Snow | From Page: RER18

James Hanna

By Zack Snow | From Page: RER18

Raul Zamora

By Zack Snow | From Page: RER19

Susan von Geldern

By Zack Snow | From Page: RER19

Travis Credit Union

By Zack Snow | From Page: RER20

Jamie Madison

By Zack Snow | From Page: RER21

Karen Waggoner

By Zack Snow | From Page: RER21

Lisa Haass

By Zack Snow | From Page: RER22

Tracy Harris

By Zack Snow | From Page: RER22

First Street Real Estate

By Zack Snow | From Page: RER24