Stock phrase in commercials for non-prescription products with some purported health benefit — especially items which are not actually health care items, such as sugar-free gum.
Sometimes phrased as "Nine out of these ten doctors agree," showing you a group of men in white coats with stethoscopes. This is a clue to what's really going on.
Your brain hears "Nine out of Ten Doctors Agree", and reads it as "90% of doctors agree." But that's not necessarily what happened — the sample size and population can be anything the advertiser wants it to be, including literally having a panel of only ten doctors asked (and cherrypicking doctors until they get the result they want).
Alternatively, the claim may reflect reality, but what is being claimed isn't the same as what is being sold: listen carefully. Did nine out of ten dentists really say that their brand of toothpaste was best, or did nine out of ten dentists just agree that toothpaste in general is a good idea? Did they say they would recommend this brand over all other brands, or did they just say they would recommend it?
In fact, if you catch wise to the fact that what the nine of ten doctors are agreeing to is something much more generic than what is being sold, you might start to wonder: What's up with the one out of ten doctors who thinks smoking is cool? As a result, it has become fashionable for some commercials to poke fun at the trope, implying that the tenth doctor would have endorsed their product, were it not for some external force (he was reaching for the "agree" button when a venomous snake bit him, sending him into a convulsion before he could agree).
For the classic disassembly of these sort of statistics, may we recommend Darrell Huff's How to Lie with Statistics? The 1950s were a lot less naive than you might assume. Indeed, this is a subtrope of Lies, Damned Lies, and Statistics.
This trope has nothing to do with Doctor Dolittle, Doctor Octopus, Doctor Faustus, Doctor Horrible, Dr. Phil, Doctor Slump, Doctor Strange, Dr. Strangelove, Doctor Fate, Doctor Zhivago, Doctor Jekyll, Doctor Wily, Doctor Manhattan, Dr. Eggman, Doctor Steel, Witch Doctors of any denomination, or any of the Doctors from Doctor Who because it's Not That Kind of Doctor, though you probably could find something at least nine of them agreed on (with the common joke being "Nine out of ten Doctors agree - Four's scarf is too long").
- The original instance of this phrase comes from Trident gum, where "four out of five dentists recommended sugarless gum for their patients who chew gum". They didn't add the qualifier "if their patients insisted on chewing gum", nor did they tell you that the fifth dentist recommended that his patients not chew gum at all. Years later, Trident would parody this device by having four out of five dentists endorse the gum, with the fifth accidentally denouncing it. (He was knocked unconscious and smashed his face on the "NO" button, had a squirrel crawl up his leg and bite him in the groin, causing him to yell "Nooooooo!" etc.)
- An extreme example: an ad for Whiskas claimed that "8 out of 10 Cats prefer Whiskas." This was later changed to "8 out of 10 owners who expressed a preference said that their cats preferred Whiskas." "Who expressed a preference" means there could be twenty thousand cats who'll eat anything for every eight Whiskas lovers, but they don't count. Another way to look at it is that it's entirely plausible 8 out of 10 cats would prefer Whiskas to, let's just say: starvation, being hit with a brick, being burned alive, or a bath. This actually gave the name to the Channel 4 Panel Show 8 Out of 10 Cats, which is all about statistics and opinion polls.
- A commercial for Tylenol stated that "9 out of 10 doctors recommend Tylenol!" The very next commercial was for Advil, stating "4 out of 5 doctors prefer Advil!" For all we know, the 10th/5th doctor just goes "What d'ya got?" After all, it's reasonable to expect you to keep on hand the one that works for you. These claims aren't necessarily mutually incompatible ... it's what goes unsaid ("in a hospital setting where we can monitor you to make sure it's not killing your liver," for example) that makes the difference.
- Stan Freberg parodied this as far back as the early 1960s with a commercial he made for Chun King Chinese food which proudly proclaimed that nine out of ten doctors recommended the product. The camera then revealed nine smiling Chinese doctors and one scowling Anglo one.
- Years ago, in the late 1980s or early 1990s, Bell Atlantic used to run TV ads for their Yellow Pages proclaiming that "9 out of 10 people use it!" Considering that this was pre-Internet, and that Bell Atlantic had little competition in the areas it served (aside from small patched served by Contel/GTE or other independents), you have to wonder what the other 10% of people used...
- Used in a BYU Library commercial modeled like an Old Spice commercial operating under Rule of Funny.
Narrator: Did you know that eight out of five dentists say that studying in the library is 6 bajillion times more effective than studying in your shower?
- One of Marvel's solicitations for Nextwave claimed "nine out of ten dentists recommend Nextwave. In fact, they recommend it so much, they beat the tenth up, and he fell into line."
- One MAD cartoon had a group of dentists cheerfully saying "Brush after every meal!" with one surly-looking holdout muttering "I'm sure you have better things to do with your time."
- Pearls Before Swine had a few comics where Pig introduced his friends, five doctors, four of which agreed on everything, the fifth of which always disagreed. This was for more than just chewing gum — they went to a funeral, and while the first four were offering their condolences, the fifth one just said, "She's dead all right."
- A strip of 9 Chickweed Lane showed a group of white-coated figures walking away from another whom they'd apparently just hanged (only his legs are shown, dangling from the top of the panel), and an onlooker remarking, "Nine out of ten doctors agreed."
- A Snow White and the Seven Dwarfs Fun T-Shirt has the message "Six out of seven dwarfs aren't Happy."
- Pokémon: Mewtwo Returns: Misty and Brock drink some water from the Purity River and love the taste. Ash drinks it and says it tastes "like something's been swimming in it." Pikachu and Togepi try it and love it.
Misty: Looks like four out of five water drinkers prefer Purity River water.
- The original Trident commercial is referenced on an early episode of Friends. Someone enters and says "Guess what!" and Chandler immediately quips, "The fifth dentist caved, and now they're all recommending Trident?"
- Parodied when The Goodies go into the advertising business in "It Might As Well Be String".
Tim: Look at this! Nine out of every ten doctors agree that people who don't eat Sunbeam sliced bread will get squashed by elephants!
Graeme: That's right. Mind you, it did take us a long time to find the right nine doctors, woo hoo hoo [makes loony signal] ... and the elephants!
- Parodied in a 2004 Corner Gas episode when Wanda admitted that she hadn't seen a dentist since 1992. Brent said, "Well, you should really try to squeeze in a visit every decade or so. Four out of five dentists recommend seeing a dentist. I don't know what the fifth guy's thinking."
- Humorous advertising-deconstruction program The Gruen Transfer has actually registered the company "Nine Out Of Ten Experts", and are offering the company's endorsement to products for a "small fee". Nine out of Ten Experts recommend The Gruen Transfer.
- RoboCop: The Series has an interesting example, nine out of ten doctors employed by a Mega-Corp recommend a drug (that is manufactured and sold by the same Mega-Corp), clearly in an attempt to invoke the trope.
- Colin Mochrie parodies this trope several times on Whose Line Is It Anyway?, primarily in skits where he acts as news anchor:
Colin: Nine out of ten Americans agree that out of ten Americans, one will disagree with the other nine!
Colin: Nine out of 10 doctors agree the tenth one should really chill out.
Colin: Nine out of ten dentists leaves one dentist.
- Parodied by David Letterman on his talk show, when he claimed that "3 out of 4 Americans make up 75% of the population."
- How I Met Your Mother references this when Ted finds out that Marshall and Lily share a toothbrush:
Ted: 4 out of 5 dentists just threw up in their mouth.
- Parodied on Fresh Off the Boat with Marvin, the Wongs' dentist neighbor, and his four dentist friends. One of them, Ted, always disagrees with the group on anything and everything.
- "Yes, mothers...nine out of ten British housewives can't tell the difference between Whizzo butter and a dead crab."
- Dying after beaming into a toxic atmosphere in Space Quest V: The Next Mutation results this quote, "4 out of 5 doctors agree that beaming into a toxic atmosphere without the proper equipment can be hazardous to your health."
- Parodied in the game Sam & Max: Reality 2.0:
Max: [describing what happened to a beat-up gumball machine] A gang of five dentists came through the other night, and four of them just started beating the hell out of it!
Sam: What did the fifth one do?
Max: He kept sobbing, and saying, "Why can't we all just get along?"
- A humorous variant in Mass Effect 2:
Tupari Drinks Machine: Nine out of ten Tupari drinkers recommend Tupari to their friends. THE LAST ONE IS ON MY LIST.
- Played for laughs in Assassin's Creed: Brotherhood: a doctor who's treating your bullet wounds will mention that four out of five doctors would use leeches, lucky for you he's the fifth.
- A strip in Legostar Galactica has this. It turns out that the doctor being talked to is the tenth.
- Biter Comics: Turns out, the fifth dentist has a business minor, and would rather you not take care of your teeth at all so that you'll stay a repeat "customer". He's better than the one with an art minor, though...
- Inverted in The Bird Feeder #15, "Statistics." Josh states that he's heard one out of three birds has yellow feathers, while standing in a group of three birds, none of which have yellow feathers.
- This spanish webcomic◊ shows a dentist just talking with his secretary when he is assassinated. Then the sniper tells that the last target has been disposed. With the news saying that statistics shows that 10 out of 10 dentists recommend sugar-free gum.
- This comic◊ shows what ends up happening to the doctor who doesn't recommend the product. It translates to the sentient toothpaste tubes saying, "So you are not interested recommending us?" while the caption translates to, "One in ten dentists..."
- The Swedish humorist site Skrattnet used to have a tagline that translates into "Skrattnet, because 20 out of 10 schizophrenics recommend us."
- SpongeBob SquarePants has the '50s Krusty Krab ad with this line:
"Yes folks, nine out of ten doctors recommend eating at least one Krabby Patty a day to maintain a healthy lifestyle and a youthful positive attitude."
- The Looney Tunes films "The Major Lied Til' Dawn" and "Daffy Duck and the Dinosaur" do quick references for Wheaties cereal for the era they were released ("With cavemen, it's Duckies, 2 to 1").
- Commissioner Harry Anslinger, the first commissioner of the Federal Bureau of Narcotics, campaigned to criminalize the use of marijuana in the 1930's. From The Other Wiki:
Anslinger collected dubious anecdotes of marijuana causing crime and violence, and ignored contrary evidence such as doctor Walter Bromberg, who pointed out that substance abuse and crime are heavily confounded and that none of a group of 2,216 criminal convictions he examined were clearly done under marijuana's influence, or a discussion forwarded to him by the American Medical Association in which 29 of 30 pharmacists & drug industry representatives objected to his proposals to ban marijuana. One such statement claimed that the proposal was "Absolute rot. It is not necessary. I have never known of its misuse.", although only the single dissenter (who noted he had once encountered a doctor who had been addicted to marijuana) was preserved in Bureau files.