Russel-Research-Method-in-Anthropology

320 Chapter 12
Of course, some variables are best measured by single indicators and, by
Ockham’s razor, we would never use a complex scale to measure something
when a simple scale will do. So: The function of single-indicator scales is to
assign units of analysis to categories of a variable. The function of composite
measures, or complex scales, is exactly the same, but they are used when
single indicators won’t do the job.
Indexes
The most common composite measure is a cumulative index. Indexes are
made up of several items, all of which count the same. Indexes are everywhere.
The Dow-Jones Industrial Average is an index of the prices of 30
stocks that are traded on the New York Stock Exchange. The U.S. Consumer
Price Index is a measure of how much it costs to buy a fixed set of consumer
items in the United States. We use indexes to measure people’s health risks:
the risk of contracting HIV, of getting lung cancer, of having a heart attack, of
giving birth to an underweight baby, of becoming an alcoholic, of suffering
from depression, and on and on.
And, of course, we use indexes with a vengeance to measure cognitive and
physical functions. Children in the industrial societies of the world begin taking
intelligence tests, achievement tests, and tests of physical fitness from the
first day they enter school—or even before that. Achievement indexes—like
the SAT, ACT, and GRE—affect so many people in the United States, there’s
a thriving industry devoted to helping children and adolescents do well on
these tests.
Indexes can be criterion referenced or norm referenced. If you’ve ever
taken a test where the only way to get an ‘‘A’’ was to get at least 90%, you’ve
had your knowledge of some subject assessed by a criterion-referenced index.
If you’ve ever taken a test where getting an ‘‘A’’ required that you score in the
top 10% of the class—even if the highest grade in the class were 70%—then
you’ve had your knowledge of some subject assessed by a norm-referenced
index.
Standardized tests (whether of achievement, or of performance, or of personality
traits) are usually norm referenced: Your score is compared to the
norms that have been established by thousands of people who took the test
before you.
How Indexes Work
Multiple-choice exams are cumulative indexes. The idea is that asking just
one question about the material in a course would not be a good indicator of