Correlated (9 page)

15%
of people can spin a basketball on their finger.

But among those who like horror movies,
30%
can spin a basketball on their finger.

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40%
of people are fans of
Arrested Development
.

But among those who like horror movies,
52%
are fans of
Arrested Development
.

----------------

54%
of people root for Wile E. Coyote over the Road Runner.

But among those who like horror movies,
66%
root for Wile E. Coyote over the Road Runner.

You're extremely likely to enjoy horror movies if you both:

• want a tattoo
  
• believe that churches and other places of worship should not be tax exempt
  

People who like horror movies are almost exactly as likely as the average person to:

• rather have a smiley face than an interrobang as a designated key on their keyboard
  
• have solved a Rubik's Cube
  
• have illegible signatures
  

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47%
of people know who actress Felicia Day is.

But among those who understand HTML,
59%
know who actress Felicia Day is.

----------------

46%
of people have looked at NSFW stuff at work.

But among those who understand HTML,
55%
have looked at NSFW stuff at work.

----------------

77%
of people have never purposely listened to a Justin Bieber song.

But among those who understand HTML,
85%
have never purposely listened to a Justin Bieber song.

You're extremely likely to understand HTML if you both:

• regularly back up your files
  
• are more likely to do electric work on your own than plumbing work
  

People who understand HTML are almost exactly as likely as the average person to:

• consider themselves less generous than the average person
  
• be able to differentiate between a tangerine and a clementine
  
• be able to pop a wheelie
  

Just because two things are correlated, it doesn't necessarily mean that there is a causal relationship between the two.

For instance, the rate of autism diagnoses has been rising over the past 15 years, as have sales of organic foods. That doesn't mean that the rise in one causes the rise in the other.

However, some correlations are indeed the result of a causal relationship. For instance, we know, based on empirical observations, that tall parents tend to have tall children, and short parents tend to have short children. The height of the parent is a cause (although not the only determining factor) of the child's height.

How can you tell whether a causal connection exists between two things that appear to be correlated? Ask yourself these questions:

1. How strong is the correlation between A and B? A weak correlation makes a causal relationship unlikely.

2. By what process might A cause B, or B cause A? If you can come up with a plausible process, you're on your way to establishing a causal relationship, but even then, it's possible that your explanation, while plausible, is nonetheless incorrect.

3. Can you think of any confounding variables (see page 68) that might be the root cause of both A and B? If so, that may be the more likely explanation.

4. If A didn't exist, would B continue? If B would indeed continue, then A can't be the exclusive cause of B.

32%
of people have had to make a life-or-death decision.

But among those who don't own iPods/iPads, only
21%
have had to make a life-or-death decision.

----------------

54%
of people aren't willing to pay more for organic foods.

But among those who don't own iPods/iPads,
65%
aren't willing to pay more for organic foods.

----------------

28%
of people tend to stir their drinks counterclockwise.

But among those who don't own iPods/iPads,
38%
tend to stir their drinks counterclockwise.

You're extremely likely to not own an iPod/iPad if you both:

• don't own skinny jeans
  
• dislike Avril Lavigne more than Nickelback
  

People who don't own iPods/iPads are almost exactly as likely as the average person to:

• be credit union members
  
• have served on a jury
  
• have had wisdom teeth extracted
  

40%
of people prefer Bill Clinton over Hillary Clinton.

But among those who can juggle,
59%
prefer Bill Clinton over Hillary Clinton.

----------------

53%
of people prefer the top bunk to the bottom bunk.

But among those who can juggle,
70%
prefer the top bunk to the bottom bunk.

----------------

64%
of people think the penny should be done away with.

But among those who can juggle,
80%
think the penny should be done away with.

You're extremely likely to be able to juggle if you both:

• can spin a basketball on your finger
  
• can hold your breath longer than the average person
  

People who can juggle are almost exactly as likely as the average person to:

• dislike extra chunky pasta sauce
  
• like classical music
  
• prefer to use an electric razor
  

37%
of people have used the word
obsequious
in conversation.

But among those who have served on a jury,
59%
have used the word
obsequious
in conversation.

----------------

41%
of people say they have good posture.

But among those who have served on a jury,
62%
say they have good posture.

----------------

61%
of people are fans of Penn & Teller.

But among those who have served on a jury,
82%
are fans of Penn & Teller.

You're extremely likely to have served on a jury if you both:

• have been on a cruise
  
• prefer gold-colored jewelry
  

People who have served on a jury are almost exactly as likely as the average person to:

• prefer plain M&M's
  
• oppose the “cry it out” approach to child sleep issues
  
• prefer multiple choice test questions over essay questions
  

40%
of people support capital punishment.

But among those who think Los Angelenos are cooler than New Yorkers,
55%
support capital punishment.

----------------

32%
of people are members of warehouse clubs.

But among those who think Los Angelenos are cooler than New Yorkers,
47%
are members of warehouse clubs.

----------------

26%
of people would rather change their marital status for a day than their sex.

But among those who think Los Angelenos are cooler than New Yorkers,
39%
would rather change their marital status for a day than their sex.

You're extremely likely to think Los Angelenos are cooler than New Yorkers if you both:

• prefer doughnuts to muffins
  
• are more likely to become vegetarian for health reasons than ethical reasons
  

People who think Los Angelenos are cooler than New Yorkers are almost exactly as likely as the average person to:

• have had chicken pox
  
• like a cappella music
  
• have high cholesterol
  

42%
of people are interested in going into business for themselves.

But among those who are lactose intolerant, only
14%
are interested in going into business for themselves.

----------------

46%
of people like beets.

But among those who are lactose intolerant,
68%
like beets.

----------------

46%
of people would rather ride a waterslide than a roller coaster.

But among those who are lactose intolerant,
64%
would rather ride a waterslide than a rollercoaster.

You're extremely likely to be lactose intolerant if you both:

• prefer literature classes over composition classes
  
• like onions on your burgers
  

People who are lactose intolerant are almost exactly as likely as the average person to:

• have gone glow bowling
  
• think prostitution should be legal
  
• have had athlete's foot
  

72%
of people believe it's possible to be a woman born in a man's body or vice versa.

But among Lady Gaga fans,
84%
believe it's possible to be a woman born in a man's body or vice versa.

----------------

77%
of people have a positive opinion about surrogate pregnancy.

But among Lady Gaga fans,
88%
people have a positive opinion about surrogate pregnancy.

----------------

19%
of people regularly tweet on Twitter.

But among Lady Gaga fans,
29%
regularly tweet on Twitter.

You're extremely likely to be a Lady Gaga fan if you both:

• supported Barack Obama's reelection bid
  
• consider yourself to have very little shame
  

Lady Gaga fans are almost exactly as likely as the average person to:

• have never taken an Internet hiatus
  
• own a bicycle
  
• have had an imaginary friend when they were a child
  

33%
of people think Google hasn't done a good job of adhering to its unofficial “Don't be evil” motto.

But among those who have a landline phone,
45%
think Google hasn't done a good job of adhering to its unofficial “Don't be evil” motto.

----------------

41%
of people are fans of
Arrested Development
.

But among those who have a landline phone, only
29%
are fans of
Arrested Development
.

----------------

33%
of people dislike Avril Lavigne more than Nickelback.

But among those who have a landline phone,
44%
dislike Avril Lavigne more than Nickelback.

You're extremely likely to have a landline phone if you both:

• prefer gold-colored jewelry to silver-colored jewelry
  
• watch TV news
  

People who have a landline phone are almost exactly as likely as the average person to:

• think World War III will occur in the next 25 years
  
• be unable to tell the difference between Coke and Pepsi
  
• like sea scallops
  

49%
of people think that men who wear hats indoors are committing a faux pas.

But among left-handers,
69%
think that men who wear hats indoors are committing a faux pas.

----------------

53%
of people say their closest platonic friend is more attractive than they are.

But among left-handers, only
36%
say their closest platonic friend is more attractive than they are.

----------------

31%
of people would prefer to be the world's most talented visual artist, rather than the world's most talented musician.

But among left-handers,
45%
would prefer to be the world's most talented visual artist, rather than the world's most talented musician.

You're extremely likely to be left-handed if you both:

• prefer to be photographed from your left side
  
• don't find it hard to resist picking at scabs
  

Left-handers are almost exactly as likely as the average person to:

• think sunrise is more beautiful than sunset
  
• like the smell of cedar
  
• be willing to bare it all on a nude beach