Russel-Research-Method-in-Anthropology

110 Chapter 5
Experiments
There are two ways to categorize experiments. First, in true experiments,
participants are assigned randomly, to either a treatment group or a control
group, while in quasi-experiments, participants are selected rather than
assigned. (By the way, I prefer ‘‘participants’’ to ‘‘subjects’’ when we’re talking
about people who take part in experiments.)
Second, in laboratory experiments you have the luxury of controlling
variables, while in field experiments you get far greater realism. The logic of
experiments is the same no matter where they’re done. There are, of course,
differences in experiments with people vs. experiments with rocks or pigeons
or plants. But these differences involve ethical issues—like deception,
informed consent, and withholding of treatment—not logic. More on these
ethical issues later.
True Experiments
There are five steps in a classic experiment:
1. Formulate a hypothesis.
2. Randomly assign participants to the intervention group or to the control group.
3. Measure the dependent variable(s) in one or both groups. This is called O 1 or
‘‘observation at time 1.’’
4. Introduce the treatment or intervention.
5. Measure the dependent variable(s) again. This is called O 2 or ‘‘observation at
time 2.’’
Later, I’ll walk you through some variations on this five-step formula,
including one very important variation that does not involve Step 3 at all. But
first, the basics.
Step 1.
Before you can do an experiment, you need a clear hypothesis about the
relation between some independent variable (or variables) and some dependent
variable (or variables). Experiments thus tend to be based on confirmatory
rather than exploratory research questions.
The testing of new drugs can be a simple case of one independent and one
dependent variable. The independent variable might be, say, ‘‘taking vs. not
taking’’ a drug. The dependent variable might be ‘‘getting better vs. not getting
better.’’ The independent and dependent variables can be much more subtle.
‘‘Taking vs. not taking’’ a drug might be ‘‘taking more of, or less of’’ a drug,