Unfortunately,
it's not enough just
to show that when the program or treatment
occurs the expected outcome also happens. That's because there may
be lots of reasons, other than the program, for why you observed the outcome.
To really show that there is a causal relationship, you have to simultaneously
address the two propositions:
If X, then Y
and
If not X, then not Y
Or, once again more colloquially:
If the program is given, then the
outcome occurs
and
If the
program is not given, then the outcome does not occur