Partial abstinence, as in, "We screwed on Saturday but we abstained the rest of the week."
Mutual oral and/or masturbatory sex, which when done sloppily (sorry) can result in semen ending up in all the wrong places even without coital penetration.
The TEACHING of abstinence, which is very different from the PRACTICE of abstinence.
All very good points. You'll notice that nowhere are these points discussed in the study, or even controlled for in collecting the data. So easy for these people to manipulate the data collection in order to arrive at the conclusion they were looking for in the first place. Doubtful they used a "double blind" method for data collection. Results should be thrown out as invalid and unuseful.
In their defense (which I really don't like to do), I think the point is exactly as you already indicated:
The TEACHING of it isn't effective.
Not that actual ABSTAINING isn't effective.
I.e., teaching abstinence is not getting through.
What we need is a wholesale societal change away from the baboonish hippie approach. Just teachers aren't going to be able to fight what has been jammed down all these kids' throats from the time they were toddlers - on TV commercials, in print, now on the 'net, everywhere. Sex is "the thing" and all-important!