The news release picked up by Science Daily (among others) from RAND corp about a recent study of virginity pledges touts the potential effectiveness of such pledges:
Just two problems: (1) It's not quite true, and (2) The not-quite-true part is going to be lost in the mire of the popular press reporting and mindless copying of the news.
The actual research study, published in the Journal of Adolescent Health (June 5, 2008), is actually titled: "Virginity Pledges Among the Willing: Delays in First Intercourse and Consistency of Condom Use," and unlike the news release being propagated by various consumers of headline-bites, includes the phrase "among the willing."
After careful statistical analysis to compensate for considerable pre-existing differences between pledgers and non-pledgers, the researchers
The problem though here is that those who willingly made such a virginity pledge self-selected themselves into that action. Regardless of the propensity-score weighting process to reduce selection bias, ultimately the individuals with an "inclination to pledge" chose not to and those that did pledge selected themselves into the pledge group, making that group fundamentally different from the other group. In other words, this "actually pledged" vs. "inclination to pledge" characteristic is just as likely to be a characteristic of the personality or philosophy of people who would, or would not, have delayed sexual intercourse anyway, regardless of the actual commitment to a virginity pledge, and thus might just as well serve absolutely no causal effect in the chain of events leading to delayed sexual intercourse.
In fact, the lack of causal role for the pledge is suggested by the further result that
But even if we take the data at face value, we must remember that any such pledge-increased postponement of sex occurs only among the group of adolescents already willingly inclined to make such a pledge anyway, and within that group only by less than 10 percentage pts. As the authors themselves carefully note:
I am pessimistic that the authors' more careful conclusions and recommendations will be noticed. Instead I fear we're in for more naive calls for "abstinence education" and coerced virginity pledges.
A summary of the online article appears below.
Martino, S.C., Elliot, M.N., Collins, R.L., Kanouse, D.E., Berry, S.H. (2008). Virginity Pledges Among the Willing: Delays in First Intercourse and Consistency of Condom Use. Journal of Adolescent Health, In Press
|General Methodology||National telephone survey in 2001, with follow up 1 and 3 yrs later, using a purchsed national list of households with high prob of containing a 12–17 yr-old. Parents mailed explanation of the study in advance.
|Participants and Sample Size(s)||1,461 12-17 yr-old participants in the 3-year follow-up (73% of the baseline sample), with notable attrition patterns. 47% female; 68% white; 14% African American; 12% Hispanic.
|Dependent Measures included||Questions assessing sexual behavior with someone of the opposite sex, including the extent/nature of such encounter(s), and the use of condoms;
virginity pledge status: "Have you made a public or written promise to not have sex before marriage (yes/no)?";
various other covariates, such as age, sex, race, siblings, religiosity, self-esteem, sexual knowledge, etc.
Of baseline sample of virgins, 23.8% reported having made a virginity pledge;|
More generallly: 17% had intercourse by baseline; 29% at 1-yr; 53% at 3-yr;
Of teens reporting intercourse in year prior to 3-yr follow-up, 42% reported "less than consistent condom use."
ultimately, primary question addressed was whether "among adolescents who have characteristics associated with being inclined to make a virginity pledge, making a virginity pledge delays sexual initiation."
42.4% of 12-17 yr-old virgins who were the type inclined to make a virginity pledge init'd sexual intercourse within 3 yrs in the absence of making a pledge, whereas 33.6% initiated sexual intercourse in the presence of such a pledge.
also various correlates with pledgers vs. non-pledgers, including differences in relgiosity, monitoring by parents, peer pressures, etc.
|The authors are careful to note that the "… findings should not be taken as evidence that virginity pledges should be imposed upon adolescents. For youth who want to have sex and whose social environments support doing so, pledging is not likely to be an effective means of delaying sexual initiation (and it is doubtful that sincere pledges could be elicited from such youth). These youth need sex education that helps reduce sexual risk taking and unintended pregnancy, as do the substantial number of pledgers who eventually have sex [Santelli, Ott, Lyon, Rogers, & Summers (2006)]. Moreover, it is questionable whether being coerced into making a pledge will be effective even for teens who have characteristics like those of teens who pledge voluntarily. Psychological theory would suggest that pledging will have an effect on behavior to the extent that the pledger believes he or she freely chose to make a pledge [Festinger (1957)]."
Festinger, L. (1957). A Theory of Cognitive Dissonance. Stanford University Press, Stanford, CA.
Martino, S. C., Elliott, M. N., Collins, R. L., Kanouse, D. E., & Berry, S. H. (2008). Virginity Pledges Among the Willing: Delays in First Intercourse and Consistency of Condom Use. Journal of Adolescent Health, Articles in Press, available online 6/5/2008. [doi:10.1016/j.jadohealth.2008.02.018]
Santelli, J., Ott, M. A., Lyon, M., Rogers, J., & Summers, D. (2006). Abstinence-only education policies and programs: a position paper of the Society for Adolescent Medicine. Journal of Adolescent Health, 38, 83–87.