To infer that an intervention is
the real cause of a change:
we must make sure that the
change preceded the onset of
the intervention
b.
it is sufficient to know that the
intervention is correlated with
the change.
C.
we must ascertain whether the
change is correlated with the
intervention, learn that it did
not precede the intervention,
and eliminate plausible
alternative explanations for the
change.
d.
rely on studies that avoided the
use of random assignment to
treatment conditions.
