nonexperimental research strategy and the
quasi-experimental research strategy typically involve comparison of scores
from different groups or different conditions. However, these two strategies
use a nonmanipulated variable to define the groups or conditions being compared.
The nonmanipulated variable is usually a participant characteristic (such
as male versus female) or a time variable (such as before versus after treatment).
The distinction between the two strategies is that nonexperimental designs
make little or no attempt to control threats to internal validity, whereas
quasi-experimental designs actively attempt to limit threats to internal validity.