No, a study like that would not be heavily publicized. Many politicians use "sex offenders" as a way to garner easy votes and public support. Sex offenders are demonized and no one wants to risk their career supporting them. There have been studies done, many of them. Most studies focus on behavioral therapy combined with skills training and minor talk-therapy. Also, simply because there haven’t been studies done, does not mean positive results would not exist had studies been done. It is more of a red flag to the “demonizing offenders” camp that there aren’t many studies done. Nevertheless, I’ll try to dig up some studies at work today.
Ankle monitors are already being forced on sex offenders in some areas; we'll see how that goes. However, there is also the factor of public opinion affecting recidivism rates. You may not think it has anything to do with it, but it has a lot to do with it. "Sex offenses" are simply acts society deems "deviant". In effect, what society is doing by punishing a sex offender is telling them to conform to societal norms. Then however, the public sees a sex offender and begins picketing his home, sending him death threats, and telling him he'll always and forever be a monster that can never be rehabilitated. Basically, society is on one hand telling the offender "You must conform to our norms" and then on the other hand screaming, "You'll never be a part of society, you'll always be deviant no matter what you do". Why on earth should the offender conform? There is no motivation to even try, let alone succeed. This is not dissimilar to a teenager who has been rejected by their peers. The teen generally finds some deviant subgroup and rejects the general social group- including their behaviors, values, and norms. The more the teen is labeled "weird", "different", "deviant", or "other" the more they will embrace their deviant subculture and reject the dominant group.
Given that, an ankle bracelet is likely to do more harm than good. It is, in effect, branding the offender as a “monster” and “other”. What better way to ensure that they continue to reject society’s norms and values? What better way to ensure that they will reoffend? People are so hell-bent on punishing sex offenders that they ignore routes that would actually be effective. In all reality, you’d think the public wants the offender to molest their children just so they can cry “See! The evil sex offender molested again!” If that’s not what they want, or what you want, then they should think on the fact that that is exactly what their actions are resulting in.
"Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should"- Jurassic Park