The report also suggests that tracking STD rates would be more reliable.
It certainly makes sense. However, there are studies out there which show that people are suprisingly honest in surveys. For instance, Dr. Ann Rafferty, A researcher with the Michigan Department of Health, in 1995, published a study she did in an article entitled Validity of a Household Gun Question in a Telephone Survey in Public health reports. In her survey she did a phone survey of a certain Michigan county, Michigan at the time had rather draconian handgun laws. She cross-checked her results with certain agency records to determine how honestly people answered her question about handgun ownership. What she found was that people were surprisingly candid in their answers. So the way the research is being done now (a longitudinal survey study) should suffice to get a good picture.
I also agree that something other than just "not doing it" would probably be helpful. The problem is that those pushing abstinence also believe that the Bible forbids masturbation. Those of us who were "in the trooth" know well that kind of misguided thinking and the sick reasoning that often accompanies it.
Forscher