Partial Claims and Half-Truths Help (page 2)

Updated on Sep 28, 2011

Tests and Studies

The makers of the Stain-Ex commercial know you've become a savvy shopper, so they've remade their commercial. Now the announcer tells you:

Studies show that new Stain-Ex outperforms the leading brand in laboratory tests. And it costs less per fluid ounce than Tidy!

Clearly, they've fixed their "costs less" claim. But what about their tests? Can you now safely believe that Stain-Ex is a better detergent than the leading brand?

Not necessarily. Again, what the ad says sounds great, but you have to remember that this is an ad, which means you have to question its credibility. Yourquestions should be all the more insistent because the ad doesn't tell you anything about the tests. You don't know, for example:

  • Who conducted the studies?
  • How were the studies conducted?
  • What exactly was tested?
  • What exactly were the results?

We'll spend a whole lesson talking about tests and studies later in the book. For now, however, it's important to remember that tests and studies can be manipulated to get specific results. In other words, it's important to have a healthy skepticism about tests, surveys, and studies. They should be accepted only as very tentative truths until you can find out the answers to the kind of questions asked above. I can say, for example, that "four out of five dentists surveyed recommend CleanRight toothpaste to their patients." In order for this claim to be true, all I have to do is survey five dentists—four of whom are my friends and who Iknow do recommend that toothpaste. Is my survey impartial? Certainly not. But I can now make this claim, and it sounds good to the consumer.

When analyzing studies, probably the most important thing to consider is who conducted the study. Why? Because knowing who conducts it can help determine whether or not it's legitimate. Do the conductors have anything at stake in the results? For example, if an independent consumer group conducted the Stain-Ex lab tests, would you feel better about accepting their claims as tentative truths? Absolutely; they're not very likely to be biased. But if the makers of Stain-Ex conducted the tests, the likelihood of bias is extremely high—you should be more skeptical about claims made by them.

In the real world, it's often a little more complicated than this, but you get the idea; studies and surveys are not always to be trusted.


Recently, you heard someone on a talk show claim, "The average American teenager spends 29 hours per week watching television." What's wrong with this claim, other than the fact that it's a bit disturbing?

The trouble with this claim lies in the word average—a word often misused, and often used to mislead. Here, the problem for the listener becomes defining "average." What is the average American teenager? What age? What habits? What likes or dislikes? How we define "the average American teenager" can make a big difference in determining what this claim actually means.

Sometimes, using the word average to describe something is good enough—like the average banana for example. But often, average is in the eye of the beholder. My definition of an average teenager, for example, is probably quite different from my parents' definition, and both of our definitions are probably quite different from my 15-year-old cousin's idea of the average teen.


Average is a great term to use when you are sitting in math class. It doesn't work as effectively in conversations. It also should be avoided when you're focusing on your reasoning skills. It is too easily thrown around but almost never based on facts.

The word average can also be troublesome when we're talking about numbers. Take, for example, the following advertisement:

Looking for a safe, secure place to start a family? Then come to Serenity, Virginia. With an average of ten acres per lot, our properties provide your children with plenty of space to grow and play. Our spacious lawns, tree-lined streets, and friendly neighbors make Serenity a great place to grow up!

Sounds like a terrific place, doesn't it? Unfortunately, this ad is very misleading if you think you're going to move onto a big property.

In most cases, average means mean, the number reached by dividing the total number by the number of participants. Let's take a look at how Serenity came up with this number. Here are the facts:

In Serenity, there are 100 properties. Ten of those properties have 91 acres each. Ninety of those properties have only one acre each.

10 × 91 = 910

Ten acres is the average, all right. But does that represent the majority? Does the average accurately suggest what most properties in Serenity are like? Obviously not. In Serenity, the typical house sits on just one acre, not ten.

It's important to keep in mind that average does not necessarily mean typical or usual. Unfortunately, that's generally what people think of when they hear the word average. And that's why an ad like this can be so misleading.

Partial Claims and Half-Truths In Short

Incomplete claims and half-truths can look and sound convincing. But a critical thinker like you has to be wary of such claims. When someone is trying to convince you to do something—as advertisers do hundreds of times each day, for instance—watch out for misleading claims that make their cases sound stronger than they really are.

Skill Building until Next Time

  • Pick up a popular magazine and look for ads that make incomplete claims. Compare them to ads that show more respect for your judgment and give you more information.
  • Listen carefully to others today at work, on the radio, or on TV. Do you hear any incomplete claims? Do you notice any suspicious "averages"?

Exercises for this concept can be found at Partial Claims and Half-Truths Practice.

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