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J L Rodgers

Publications and source records attributed to J L Rodgers.

24 records · Page 2Linked to original sources
PubMedDate not supplied

An "epidemic" model of sexual intercourse prevalences for black and white adolescents.

In adolescence (12-16 years), the prevalence of sexual intercourse increases each year. To explain the increasing yearly prevalences, we propose a recursive equation model of onset of adolescent sexual intercourse. The model allows for an "epidemic" process (the transmission of sexuality from a nonvirgin to a virgin) and a nonepidemic process (two virgins progressing to sexual intercourse). The model also requires that virgin females be pubertally mature before they will progress to sexual intercourse. Adequate fits were obtained to the intercourse prevalences for both black and white respondents. Comparisons of alternative models established that the full model was superior to models that omitted either the nonepidemic process or the requirement of females' pubertal maturation. The model was able to fit both white and blacks simultaneously, assuming equal transition probabilities in both races. Hence, we propose the hypothesis that race differences in sexual intercourse prevalence may be strongly influenced by the age of initiation of the "epidemic" process and by race difference in females' rates of pubertal maturation. The results suggested that most new cases of sexual intercourse arose from the epidemic process and that males were more prone to progress to intercourse, given an opportunity.

Adolescent↗
PubMedDate not supplied

Seasonality of first coitus in the United States.

Recent attention to causes of seasonality of births leads to an interest in seasonality patterns in the antecedents to birth, including gestational length, conception, and coital activity. In this paper we study the beginning of the process: first intercourse among adolescents and young adults. Analysis of a small and local dataset is suggestive that loss of virginity is particularly likely during the summer. A test of this "Summer Vacation Theory" using a large national dataset supports the generality of the phenomenon. Further, a prediction that seasonality patterns will change during the transition from high school to work and college is tested and supported. The existence of both biological and psycho-social mechanisms is suggested. Policy implications are reviewed.

Adolescent↗
PubMedDate not supplied

A social contagion model of adolescent sexual behavior: explaining race differences.

Black adolescents in the United States consistently report an earlier age of first intercourse than White adolescents. Purely psychosocial explanations of this finding have been less than successful. We propose an "epidemic" model that combines social contagion (a psychosocial process) and pubertal maturation (a biological process). This epidemic model permits social contacts among adolescents of the same age and also among younger and older adolescents. The model statistically fit the actual growth curve of sexuality well for Whites; its fit was not as good for Blacks. From computer simulation analyses, we concluded that pubertal maturation may be more important in accounting for the racial difference in the onset of sexual intercourse than previously thought.

Adolescent↗
PubMedDate not supplied

Seasonality of birth in nineteenth- and twentieth-century Austria.

We present an analysis of birth seasonality in nine geographical regions within Austria for two time periods, 1881-1912 and 1947-1959. In the early period, geography, climate, and agricultural patterns were related to birth seasonality. By the latter time period, these factors were no longer related to birth seasonality. We propose a "resilience hypothesis," which suggests two levels of causal influences on birth seasonality. First, underlying the three significant features of birth seasonality patterns around the world are only a small number of major causes. But, second, there are a multiplicity of minor causes that result in small perturbations in these otherwise resilient and consistent patterns.

Agriculture↗