TED Talks · Am I Normal

Do 9 out of 10 dentists really recommend that toothpaste_

When it comes to toothpaste commercials, you've probably heard claims like 9 out of 10 dentists recommend brighter whiter.

Level: B1 · 48 sentences

Transcript

  1. When it comes to toothpaste commercials,
  2. you've probably heard claims like 9 out of 10 dentists recommend brighter whiter.
  3. Or maybe it's 4 out of 5 or 80%.
  4. But either way, these companies expect you to see a wall of white coats,
  5. trust their authority, and think no further.
  6. Now that approach is basically BS.
  7. And you probably know it's BS.
  8. But the question is, how can you trust your BS radar?
  9. Well, when I'm faced with suspicious statistics,
  10. I tend to ask myself three questions.
  11. First, what were people actually asked?
  12. Sometimes the question that is put to survey respondents is wildly different than the one that ends up on posters and billboards.
  13. For instance, in 2007,
  14. one toothpaste ad in the UK claimed that more than 80% of dentists recommended their product.
  15. What that sounds like is that a majority of dentists preferred their product over all others,
  16. that those dentists were asked if this was the best product.
  17. But when the Advertising Standards Authority looked into it,
  18. they discovered that the dentists were asked to recommend several toothpastes,
  19. not one single choice.
  20. In fact, another brand was found to be almost as popular.
  21. To no one's surprise, the ad was deemed misleading.
  22. Now, the second question to ask is, what aren't you telling me?
  23. In the 1970s,
  24. a sugarless gum company claimed that four out of five dentists recommended their product.
  25. Now, their slogan was pretty upfront about the fact that these dentists were only recommending the product to people who already chewed gum.
  26. but they weren't so forthcoming about the fifth dentist.
  27. Decades later, the manufacturer made fun of it in a new ad campaign where they blamed the fifth dentist's different thinking on a freak accident like a sudden squirrel bite.
  28. Now, since I'm all about the deviations in the data,
  29. I decided to look into this a little bit further.
  30. In fact, it's not that the fifth dentist recommended chewing sugary gum.
  31. What they don't say is that most of them recommended that their patients don't chew gum at all.
  32. The last thing to ask is, what was the survey context?
  33. Because there's a really big difference between saying nine out of 10 dentists agree and nine out of these 10 dentists agree.
  34. Size matters, and so does methodology.
  35. According to the American Dental Association,
  36. there are about 200,000 registered dentists in the US.
  37. Now I'm not gonna bore you with the maths here,
  38. but to get a statistically significant sample of 200,000 people, you need about 400.
  39. So if you're reading in the fine print that only 50 dentists were surveyed,
  40. you know that's not statistically significant.
  41. It's just a marketing ploy.
  42. So the next time you see one of these ads,
  43. Ask yourself, what were people actually asked?
  44. What's gone unsaid?
  45. And what was the survey context?
  46. Hopefully with those three questions and a little bit of skepticism,
  47. you will be able to understand when the data is legit and when it's irrelevant.
  48. Nine out of 10 monas agree.