As a matter of semantics, we have not proved the null hypothesis to be true (that substance abuse treatment has no effect). It may turn out to be extremely effective for ciother group of prisoners. Or perhaps many more of the prisoners in this treatment group would have been rearrested if they had not received the treatment. In any case, i the basis of the data collected, we have merely failed to reject our null hypothesis, here is a similar, distinction between “failing to reject” a null hypothesis and accept- g that null hypothesis. Just because one study could not disprove that substance abase treatment has no effect (yes, a double negative) does not mean that one must accept that substance abuse treatment is useless. There is a meaningful statistical I sanction here. That said, research is often designed to inform policy, and prison officials, who have to decide where to. allocate resources, might reasonably accept the : ration that substance treatment is ineffective until they are persuaded otherwise, ere, as in so many other areas of statistics, judgment matters.