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Math - Validity of Percentages Used in Ads

by Tee
(USA)











































In recent article, the author states that 71% of adults do not use sunscreen. Although 71% is a large percentage, explain why this could be misleading?

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Jul 21, 2011
Validity of Percentages Used in Ads
by: Staff


The question:

In recent article, the author states that 71% of adults do not use sunscreen. Although 71% is a large percentage, explain why this could be misleading?


The answer:

There are many possible reasons why the 71% figure could be misleading.

A good place to start understanding the 71% figure is to consider the 6 W’s.

Kipling’s poem makes it easy for us to remember:

I keep six honest serving-men
(They taught me all I knew);
Their names are What and Why and When
And How and Where and Who.


We might be temped to assume that the author is talking about people not using sunscreen in the hot sun, but the author doesn’t say.


That said, begin with the first W: What

What is the writer talking about? The subject is “Not using Sunscreen.”


The second W: Why

Why is the author writing about “Not using Sunscreen”? Is there not enough sunscreen available (in retail outlets) for everyone who wants it? Is the author’s company selling sunscreen? Is the author warning against skin cancer? Is the author just writing an article to build a resume?


The third W: When do 71% of adults not use sunscreen?

On vacation? While they are at work? When they are at the movies? When they go to sleep at night?


The fourth W: How


The fifth W: Where

Where do people not wear sunscreen? at the office, traveling to and from work, or watching TV at home. It is probably not necessary to wear sun screen 95% of places we go. Or . . . is the author talking about not wearing sunscreen at the beach?


The sixth W: Who


This question is answered to some minimal extent: adults. But what adults? (male, female, adults in Iceland, adults in Mexico, adults in prison, adult baseball players, etc.)


We could go on, but the fact is that no details are provided to support the claim. The 71% figure is not explained.

The author could have said that 71% of adults do wear sunscreen and been just as accurate by referring to adults who are water skiing.

Once these questions are answered, specific concerns regarding the mathematics behind the figure can be addressed. For example: what sample size was used to arrive at the 71% figure? What is the margin of error? How and where was the sampling conducted?



Thanks for writing.

Staff
www.solving-math-problems.com



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