with sexual partners. The second factor is the number of uninfected individuals that are in the population. At the beginning of an epidemic, a sexually-transmitted disease spreads when the uninfected partner of an infected person becomes highly sexually-active within the population, leading to an increase in the amount of those infected. As the population becomes more infected, an infected person will be less likely to encounter an uninfected one, leading to a decline in new infections. However, although the rate of new infections of HIV among older gay males has decreased, it is dangerous to say that the same pattern has been observed for gay adolescents. Similarly, data suggests that heterosexual adolescents also engage in anal intercourse which can lead to an increase in the number of infected persons. 10% of women at an adolescent planning center, 19% of female Canadian college students, and 25% of Black and Hispanic women at a family planning center all reported engaging in anal-intercourse with their partners. The statistics suggest that there is an increasing need for research on the sexual risk-behaviors of adolescents. The current research on adolescent risk-taking sexual behaviors lack three fundamentals conditions that would give sufficient and generalizable data on the current sexual-behaviors of adolescents. The first is that the research studies need to have large samples and thorough designs to cover the diverse populations of adolescents that range from various genders, sexual orientations, ethnicities, races, and cultures. Second, there needs to be research that studies the interaction between various social contexts, such as riding in cars for enjoyment, and adolescent sexual-behaviors that leave youth susceptible to engaging in sexual-intercourse. Lastly, it would be necessary for repeated longitudinal studies on the sexual behaviors of adolescents as behaviors are constantly changing and may be open to different interpretations. The American Teen Study would have been utilized to conduct the type of research that would be needed to investigate the increasing rate of sexually-transmitted diseases among adolescents. The authors (1993) suggest that the cancellation of The American Teen Study was politically motivated as evidenced by Louis Sullivan's rushed rejection of the study without providing adequate reasoning for why the study should not take have taken place. Without data from the study, it can be difficult for scientists to monitor the spread of sexually-transmitted diseases such as HIV and to develop techniques to decrease the increasing rate of infections. See also Age disparity