Chapter 8 Experiments Flashcards
pretesting
The measurement of a dependent variable among subjects before they are exposed to a stimulus representing an independent variable.
posttesting
The remeasurement of a dependent variable among subjects after they’ve been exposed to a stimulus representing an independent variable.
experimental group
In experimentation, a group of sub- jects to whom an experimental stimulus is administered.
control group
In experimentation, a group of subjects to whom no experimental stimulus is administered and who resemble the experimental group in all other respects. The comparison of the control group and the experimental group at the end of the experiment points to the effect of the experimental stimulus.
Diagram of basic experimental design
the fundamental purpose of an experiment is
to isolate the possible effect of an independent variable (called the stimulus in experiments) on a dependent variable. Members of the experimental group(s) are ex- posed to the stimulus and those in the control group(s) are not.
double-blind experiment
An experimental design in which neither the subjects nor the experimenters know which is the experimental group and which is the control.
Randomization
A technique for assigning experimental subjects to experimental and control groups randomly.
Matching
In connection with experiments, the procedure whereby pairs of subjects are matched on the basis of their similarities on one or more variables, and one member
of the pair is assigned to the experimental group and the other to the control group.
Internal invalidity
Refers to the possibility that the conclusions drawn from experimental results may not accurately reflect what went on in the experiment itself.
The Solomon four-group design
The classical experiment runs the risk that pretesting will have an effect on subjects, so the Solomon four- group design adds experimental and control groups that skip the pretest. Thus, the Solomon four-group design combines the classical experiment and the after- only design or “static-group comparison.”
External invalidity
Refers to the possibility that conclu- sions drawn from experimental results may not be generaliz- able to the “real” world.
Field experiment
A formal experiment conducted outside the laboratory, in a natural setting.
The classical experiment
The classical experiment tests the effect of an experimental stimulus (the independent variable) on a dependent variable through the pretesting and posttesting of experimental and control groups.
“Natural” experiments
Natural experiments often occur in the course of social life in the real world, and social re- searchers can implement them in somewhat the same way they would design and conduct laboratory experiments.
