Advertising claims

The purpose of this activity is to get students to think critically about the statistics presented to them in the media or, as in these examples, advertising that claims statistical backing.

For each part of question 1, encourage your students to discuss what the statement is saying and, perhaps more importantly, what is it not saying. Discuss how the statistic or the data may have been obtained. Students at this level may not be fully aware of the ways in which data can be manipulated in order to present a desired picture for advertising (for more on this see Spin Doctor on pages 16–17).

Some examples of questions and activities to get students thinking critically are:

• For a, ask the students what they think the dentists were actually asked in the survey. The question “Which brand of toothbrush do you use?” and the question “Have you ever used a Bubbles toothbrush?” will result in a differing amount of Bubbles “users”. You could ask your class these kinds of questions and see if the results are significantly different. You could also ask them about the sample of dentists.
  • How big was it?
  • What population of dentists did it come from? (New Zealand? America?)
  • Were the dentists selected randomly?
  • Is it possible to select dentists randomly?
• For b, get the students to find some “low-fat” products and compare with the full-fat counterparts to see how much less fat each low-fat product really has. It is also useful to look at sugar content because some low-fat products replace fat with extra sugar.
• For c, this statement provides a good lead-in to a blind taste test. For example, get two known brands of orange juice and have 10 students do a blind tasting and state which they prefer. Then repeat the experiment, but have 10 different students comparing the losing brand to a watered-down version of the winning brand from the first experiment. Discuss how the preference for one brand depends on what it is being compared with.
• For d, ask the students to fi nd out what number of books must be sold to define a best seller in New Zealand and how best-seller ratings are done in New Zealand. They can then debate how reliable or meaningful the ratings are. (They could do an Internet search on “New Zealand best seller sales figures”.) Have them compare this information with that for another country, such as the United States, and discuss why the numbers are different.
• For e, discuss the ways in which a magazine’s own ranking system may not be purely objective. Ask the students if they think magazines get paid by manufacturers to promote their product.

When the students are critiquing real advertisements in question 2, have them ask and attempt to answer questions such as:

• Who was surveyed?
• How many people were surveyed?
• How were the participants chosen?
• What survey questions were asked?
• What was tested?
• What did the test involve?
• What is this statistic actually saying? What is it not saying?
• What assumptions have been made?

The students may find it useful to use the PPDAC cycle when they are critiquing because every stage of the cycle can be questioned in relation to the quoted statistic. In other words, the advertiser is just presenting the “conclusion” phase – the other steps must be assumed and can therefore be questioned.

1.

a.

• i. Because they are perceived as experts in this matter.
• ii. Answers will vary. It could have been as few as 5.

b.

• i. No
• ii. This product contains only 10% of the amount of fat that other (unnamed) brands do. (However, we don’t know how much fat any of the products contain. The advertised product could still have more fat in it than health experts recommend.)
• iii. The advertiser might hope that people would think that the “other leading brands” would have 90% fat in them and that the advertised product is low in fat. “90% less fat” sounds healthy!

c.

• i. In this case, it means the survey was not conducted by the manufacturers of Superfroth shampoo.
• ii. So that it sounds believable and unbiased
• iii. Answers may vary. We don’t know what else was in the survey.

d.

• i. The term “best seller” is used very loosely. It probably means that the book has sold a certain number of copies, or more copies than other books have. (However, best-seller sales claims from trade associations are evidence-based.)
• ii. Sales figures
• iii. Not necessarily. The writing of many popular authors is not always of a high standard or well researched, although they may tell a good story. Some of the first books written by an author may be very good, but once an author is famous, their books may sell because of fame rather than quality.
• iv. Many books could be if “best seller” means a certain number of copies.
• v. Answers will vary, for example, sales figures, the amount of promotion and advertising, whether it is a book by a well-known author (therefore eagerly awaited regardless of quality), whether the term is applied to the book by the publisher to promote sales, and so on.

e.

• i. Answers will vary. In this context, it could mean the current year’s model.
• ii. You can’t tell from the statement.
• iii. Answers will vary. If the survey is not an independent one, it could be very few, and they could all be biased!

2.

Critiques and discussion will vary.

"Advertising claims" can be used to develop these key competencies:

• thinking: challenging assumptions, engaging in making sense, and evaluating
• using language, symbols, and texts: demonstrating statistical literacy
• relating to others: accepting and valuing different viewpoints and negotiating meaning