Russel-Research-Method-in-Anthropology

Research Design: Experiments and Experimental Thinking 115
ment. Consider the following experiment: Start with a group of teenagers on
a Native American reservation and follow them for the next 60 years. Some
of them will move to cities, some will go to small towns, and some will stay
on the reservation. Periodically, test them on a variety of dependent variables
(their political opinions, their wealth, their health, their family size, and so
on). See how the experimental treatments (city vs. reservation vs. town living)
affect these variables.
Here is where the maturation confound enters the picture. The people you
are studying get older. Older people in many societies become more politically
conservative. They are usually wealthier than younger people. Eventually,
they come to be more illness prone than younger people. Some of the
changes you measure in your dependent variables will be the result of the various
treatments—and some of them may just be the result of maturation.
Maturation is not just about people getting older. Social service delivery
programs ‘‘mature’’ by working out bugs in their administration. People
‘‘mature’’ through practice with experimental conditions and they become
fatigued. We see this all the time in new social programs where people start
out being really enthusiastic about innovations in organizations and eventually
get bored or disenchanted.
3. Testing and Instrumentation
The testing confound happens when people change their responses in reaction
to being constantly examined. Asking people the same questions again
and again in a longitudinal study, or even in an ethnographic study done over
6 months or more, can have this effect.
The instrumentation confound results from changing measurement instruments.
Changing the wording of questions in a survey is essentially changing
instruments. Which responses do you trust: the ones to the earlier wording or
the ones to the later wording? If you do a set of observations in the field and
later send in someone else to continue the observations you have changed
instruments. Which observations do you trust as closer to the truth: yours or
those of the substitute instrument (the new field researcher)?
In multi-researcher projects, this problem is usually dealt with by training
all investigators to see and record things in more or less the same way. This is
called increasing interrater reliability. (More on this in chapter 17, on text
analysis.)
4. Regression to the Mean
Regression to the mean is a confound that can occur when you study
groups that have extreme scores on a dependent variable. No matter what the