What the research literature clearly says is that there is a lack of conclusive evidence to demonstrate that it either works or doesn't work. Studies are sometimes contradictory. We get some results that are positive, some that are negative, and some that show no effect. When you take a look at all of the work that's been done, what you conclude is that there's no evidence to say that it contributes to reducing recidivism.
One thing that a number of the studies show is that it does help the person through the period of time during which they're on electronic monitoring. For the short period of time they're being monitored, they're more likely to comply with their conditions. Most of the research is based on the use of electronic monitoring for ensuring a condition of curfew or of living in a residence, such as with a conditional sentence or an early release. Essentially it's a house arrest following an early release.