| What
is Scientifically Based Research?
Quasi-experimental
Research
We
know that large-scale, random assignment experiments
allow us to have a maximum level of certainty about
the impact of interventions. We also know that more
and more researchers are finding out how to conduct
true experimental research in schools. However, there
are situations in which random assignment of individual
participants to experimental and control conditions
may not be possible and an alternative research method
is sought.
There
are alternatives to experimentation that can attain
a comparatively high degree of certainty while largely
avoiding the barriers sometimes encountered when attempting
to implement true experiments. Chief among these techniques
are quasi-experimental studies. Where
large-scale, randomized experiments do the best job
of ruling out all unrelated explanations and leave only
the experimental intervention as a viable explanation
for measured outcomes, quasi-experimental methods focus
on eliminating specific alternative explanations by
constructing various types of specialized comparisons.
Among the most important types of quasi-experimentation
are:
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