The number of criminals put under routine supervision was not significantly greater than the number of criminals put under intensive supervision. Of the criminals arrested while under intensive supervision, some would not have committed crimes if they had been under routine supervision. All of the criminals who were arrested while under routine supervision had been in prison more than once before being paroled and put under supervision. The proportion of arrests to crimes committed was not significantly higher for criminals under intensive supervision than for those under routine supervision.
Criminals released from prison on parole have generally been put under routine supervision. A recent program has allowed criminals to leave prison early under intensive supervision; they must obey curfews and in some cases they must be electronically monitored. The percentage of released criminals arrested while under supervision is the same for intensive supervision as for routine supervision, so intensive supervision is no more effective than routine supervision in preventing criminals from committing additional crimes.
Which one of the following is an assumption on which the argument relies?