Newspaper headlines sometime ask a question, and the answer to that question is usually “no.” If the answer is “yes,” then it’s a fact and there would be no reason to ask a question. The questions are often sensational (“Will coffee kill you?” is one example) and “no” is the usual answer to a wild rumor.
 
The origin of the adage is unknown. The name “Hincliffe’s Rule” was applied by at least 1988. “DAVIS’ LAW: If a headline ends in a question mark, the answer is ‘no’” was cited in 1991.
 
“This story is a great demonstration of my maxim that any headline which ends in a question mark can be answered by the word ‘no’” was written by British technology journalist Ian Betteridge in 2009, and it’s sometimes called “Betteridge’s law of headlines.” “Is Betteridge’s law of headlines correct?” is a joke that became popular in 2011.
   
 
Wikipedia: Betteridge’s law of headlines
Betteridge’s law of headlines is an adage that states: “Any headline that ends in a question mark can be answered by the word no.” It is named after Ian Betteridge, a British technology journalist, although the general concept is much older. The observation has also been called “Davis’ law” or just the “journalistic principle”. In the field of particle physics, the concept, referring to the titles of research papers, has been referred to as Hinchliffe’s Rule since before 1988.
     
Inspire
Is Hinchliffe’s Rule True?
Boris Peon
Aug 4, 1988 - 1 pages
Submitted to: Annals Gnosis
Print-88-0582
 
Google Books
The Complete Murphy’s Law:
A Definitive Collection
By Arthur Bloch
Los Angeles, CA: Price Stern Sloan
1991
Pg. 163:
DAVIS’ LAW: If a headline ends in a question mark, the answer is “no.”
 
Google Groups: alt.atheism
Therion Ware  
8/18/04
(...)
Heh. This was in many of our down market tabloids today. “Is the is chamber of John the Baptist?” and so on.
 
Years ago, a media guy told me that in 99.7% of cases, when a newspaper asks a question in a headline, the answer is “no”.
     
Technovia (UK)
TechCrunch: Irresponsible journalism
by IAN BETTERIDGE on FEBRUARY 23, 2009
(...)
One thing though: This story is a great demonstration of my maxim that any headline which ends in a question mark can be answered by the word “no”. The reason why journalists use that style of headline is that they know the story is probably bullshit, and don’t actually have the sources and facts to back it up, but still want to run it. Which, of course, is why it’s so common in the Daily Mail.
 
Twitter
Alex Williams‏
@podcasthotel  
whenever you see a question in a headline the answer is no. #backlash? no.  http://bit.ly/NBSsB
9:56 AM - 18 Apr 09  
 
Google Books
The Reverberator:
A Novel
By Henry James
New York, NY: Macmillan and Co.
1888 (2013 reprint)
Pg. ? (This appear to be from a modern introduction—ed.):
On the front page of the same New York World that contained poor May McClellan’s charming Italian diary, there ran a story with the hysterical headline “ARE THE RICH GROWING POORER?” “There is great poverty and much unseen suffering in New York, beyond doubt,” it noted. “But it is a city imperial in wealth and luxury.” The story went on, about the art, the jewels, the newly rich, the “waters studded with pleasure yachts, floating palaces.”  The story went on, about the art, the jewels, the newly rich, the “waters studded with pleasure yachts, floating palaces.” In the end, the answer to the headline, as it is to almost every question in a headline, turned out to be “no.”
 
SA Mathieson
Is the answer to a question-marked headline always no?
Posted on February 25, 2013 by SA Mathieson
No. Not always. Just quite often, like just now.
 
Looking at recent articles about the NHS picked up by @ImpatientNHS with question marks in their titles, there are several variants of the question-marked headline, and they don’t all mean ‘no’.
(...)
So: is the answer to a question-marked headline ever yes?
 
Yes, it’s just rare. What it does indicate pretty reliably (when it’s not actually asking a question) is that the publication isn’t certain about the headline as a statement.
 
Twitter
Raf Sanchez‏
@rafsanchez  
America catches up w @JohnRentoul’s #QTWAIN RT @campbellnyt: Journalism rule: if there is a question in a headline the answer is always no.
12:20 PM - 14 Aug 13
 
Twitter
David Dick‏
@CarlosDebacle  
Old newspaper adage: If there is a question in a headline, then the answer is almost certainly no. Exhibit 5,312,476 http://www.theguardian.com/science/sifting-the-evidence/2013/aug/19/coffee-drinking-study-report …
7:44 AM - 20 Aug 13