Writer and feminist Eve Ensler criticizes purity balls for implying that fathers, rather than young women themselves, have the freedom to control whether and with whom the young women engage in sexual intercourse. "Glamour" claims that National Longitudinal Study of Adolescent Health data supports the conclusion that teenagers making virginity pledges, including those promulgated through purity balls, usually do not adhere to the required standard of chastity, and are less prepared to utilize safe sex practices to mitigate the risks when engaging in sexual activity. Furthermore, Glamour states that the percentage of teenagers in a given area who have made virginity pledges is positively correlated with the frequency with which sexually transmitted infections occur. An article in "Time" magazine says that there is a scientific controversy as to the efficacy of the virginity pledges at purity balls.