The biased sample
"There are
more black men in prison than in college."
This is one of
those two sided facts that the right will use to make a racist point and the
left will use to make an antiracist point.
1) But is it even
relevant?
Anyone have any
suspicions?
This is a
comparison of two groups. The group of all black men in college, and the group
of all black men in prison.
Here's a thought.
You go into college at 4 years, but in prison you could stay in for 10, 15, 20
years.
But to put it even
clearer. The group of college age black men is the group from which the group
of black men in college is drawn. Right?
2) Am I making a
reasonable statement here?
Black men in college
are college-aged.
What about black
men in prison? Well, they could be any age (and are-- yes it's true youth
commit more crime, but remember that people stay in prison for years and
years).
So, next question:
3) What's a bigger
group, the group of all black men or the group of college aged black men?
For the group of
black men in college, we're drawing from the group of college aged black men.
For the group of black men in prison, we're drawing from the group of all black
men.
An even better example of this phenomenon,
to stay on the racial issue, is one employed by new school racists: "American
Blacks are lazy. Caribbean immigrants are black and their unemployment rate is
lower than American Blacks. So it isn't racism-- it's cultural
deficiency".
Well, at least they're off the 'genetic
deficiency' bandwagon. Let's leave that aside. Let's leave aside also the
assumption that unemployment and laziness are equivalent. This argument also
depends on a biased sample.
Where's the bias? Well, those who can afford
to immigrate are often those with some education, connections, and wealth.
People with those things have a better chance of success. So the Caribbean
example compares relatively wealthy, educated, connected immigrants with all
American Blacks. Again, I'm attacking the statistical validity of the
statement, not the moral bankruptcy of making these comparisons in the first
place.
Lesson: Any time you hear someone compare
groups, ask who's in the group and who's left out, and if that's convenient for
the conclusion they're trying to convince you of.