Russel-Research-Method-in-Anthropology

34 Chapter 2
Dependent and Independent Variables
Beginning in the 1840s, breakthroughs in sociology and anthropology produced
insight into the impact of economic and political forces on demography.
One practical result of all this work was life insurance. The way life insurance
works is that you bet the company that you’ll die within 365 days. You answer
a few questions (How old are you? Do you smoke? What do you do for a
living? Do you fly a small plane?), and the company sets the odds—say, your
$235 against the company’s promise to pay your heirs $100,000 if you win
the bet and die within 365 days. But if you lose the bet and stay alive, they
keep your $235, and next year you go through all this again, except that now
the odds are raised against you to say, your $300 against the company’s promise
to pay your heirs a lot of money.
For insurance companies to turn a profit, they have to win more bets than
they lose. They can make mistakes at the individual level, but in the aggregate
(that is, averaging over all people) they have to predict longevity from things
they can measure.
Longevity, then, is the dependent variable, because it depends on sex, education,
occupation, etc. These latter are called independent variables because
they are logically prior to, and therefore independent of, the dependent variable
of longevity. How long you live doesn’t have any effect on your sex. In
our earlier example, blood pressure was the dependent variable. There is no
way skin color depends on a person’s blood pressure.
It’s not always easy to tell whether a variable is independent or dependent.
Does high female infant mortality among Amazonian tribal people depend on
high levels of warfare, or is it the other way around? Does high income depend
on having a lot of land, or vice versa? Do inner-city adolescent girls get pregnant
because they are poor, or . . . ? Does the need for litigation stimulate the
production of attorneys, or . . . ?
Failure to understand which of two variables depends on the other is the
source of endless shenanigans. One of my teachers, Oscar Lewis (1961, 1965),
described what he called a ‘‘culture of poverty’’ among slum dwellers in cities
around the world. People who live in a culture of poverty, said Lewis, are not
very future oriented. This plays out, he said, in their shopping for food every
day and in never buying large economy sizes of anything. Lewis’s point was
that truly poor people can’t invest in soap futures by buying large boxes of it.
He saw a low level of expressed orientation toward the future, then, as the
dependent variable and poverty as the independent variable.
Many people interpreted Lewis’s work as meaning exactly the opposite:
that poverty is caused by a low level of future orientation. According to this
topsy-turvy, victim-blaming reasoning, if poor people everywhere would just