Editing data: what difference do consistency checks make?
In 1998, the Florida Department of Health undertook a self-administered school-based survey of tobacco use, attitudes, and behaviors among nearly 23,000 public school students in grades 6-12. The survey design did not use skip patterns; therefore, students had multiple opportunities to contradict themselves. By using examples from the high school portion (grades 9-12) of the survey, the authors examined five possible approaches to handling data inconsistencies and the effect that each has on point estimates. Use of these approaches resulted in point estimates of current cigarette use ranging from 25.6% to 29.7%. The number of missing respondents varied from 33 (less than 1%) to 1,374 (13%), depending on which approach was used. After stratification by gender and race, the prevalence estimates changed marginally for girls but strikingly for boys. Non-Hispanic White students were substantially more likely than non-Hispanic Black students to report current cigarette use, but the magnitude of this difference varied significantly according to the analytical approach used. The approach used to check data consistency may influence point estimates and comparability with other studies. Therefore, this issue should be addressed when findings are reported. (+info)
A simple method for anzlyzing multifactorial data.
A simple method of isolating significant factors from multifactorial data has been outlined. The factors must be at two levels, but any number of factors can be handled. Variable group sizes and empty groups do not invalidate the method. (+info)
Network-related mechanisms may help explain long-term HIV-1 seroprevalence levels that remain high but do not approach population-group saturation.
In many cities, human immunodeficiency virus (HIV)-1 seroprevalence among drug injectors stabilizes at 30-70% for many years without secondary outbreaks that increase seroprevalence by 15% or more. The authors considered how HIV-1 incidence can remain moderate at seroprevalence levels that would give maximum incidence. Previously suggested answers include behavioral risk reduction and network saturation within high-risk subgroups. Among 767 drug injectors studied in 1991-1993, during a period of stable high seroprevalence in New York City, risk behaviors remained common, and networks were far from saturated. The authors suggest a different network-based mechanism: in stable high-prevalence situations, the relatively small sizes of subnetworks of linked seronegatives (within larger networks containing both infected and uninfected persons) may limit infectious outbreaks. Any primary infection outbreak would probably be limited to members of connected subcomponents of seronegatives, and the largest such subcomponent in the study contained only 18 members (of 415 seronegatives). Research and mathematical modeling should study conditions that may affect the size and stability of subcomponents of seronegatives. Finally, if the existence of small, connected components of seronegatives prevents secondary outbreaks, this protection may weaken, and vulnerability to new outbreaks increase, if HIV-1 seroprevalence falls. Thus, in situations of declining prevalence, prevention programs should be maintained or strengthened. (+info)
Sexual networks and sexually transmitted infections: a tale of two cities.
Research on risk behaviors for sexually transmitted infections (STIs) has revealed that they seldom correspond with actual risk of infection. Core groups of people with high-risk behavior who form networks of people linked by sexual contact are essential for STI transmission, but have been overlooked in epidemiological studies. Social network analysis, a subdiscipline of sociology, provides both the methods and analytical techniques to describe and illustrate the effects of sexual networks on STI transmission. Sexual networks of people from Colorado Springs, Colorado, and from Winnipeg, Manitoba, Canada, infected with chlamydia during a 6-month period were compared. In Winnipeg, 442 networks were identified, comprising 571 cases and 663 contacts, ranging in size from 2 to 20 individuals; Colorado Springs data yielded 401 networks, comprising 468 cases and 700 contacts, ranging in size from 2 to 12 individuals. Taking differing partner notification methods and the slightly smaller population size in Colorado Springs into account, the networks from both places were similar in both size and structure. These smaller, sparsely linked networks, peripheral to the core, may form the mechanism by which chlamydia can remain endemic, in contrast with larger, more densely connected networks, closer to the core, which are associated with steep rises in incidence. (+info)
Methods and measures for the description of epidemiologic contact networks.
This article describes new methods to characterize epidemiologic contact networks that involve links that are being dynamically formed and dissolved. The new social network measures are designed with an epidemiologic interpretation in mind. These methods are intended to capture dynamic aspects of networks related to their potential to spread infection. This differs from many social network measures that are based on static networks. The networks are formulated as transmission graphs (TGs), in which nodes represent relationships between two individuals and directed edges (links) represent the potential of an individual in one relationship to carry infection to an individual in another relationship. Network measures derived from transmission graphs include "source counts," which are defined as the number of prior relationships that could potentially transmit infection to a particular node or individual. (+info)
Social ties and mental health.
It is generally agreed that social ties play a beneficial role in the maintenance of psychological well-being. In this targeted review, we highlight four sets of insights that emerge from the literature on social ties and mental health outcomes (defined as stress reactions, psychological well-being, and psychological distress, including depressive symptoms and anxiety). First, the pathways by which social networks and social supports influence mental health can be described by two alternative (although not mutually exclusive) causal models-the main effect model and the stress-buffering model. Second, the protective effects of social ties on mental health are not uniform across groups in society. Gender differences in support derived from social network participation may partly account for the higher prevalence of psychological distress among women compared to men. Social connections may paradoxically increase levels of mental illness symptoms among women with low resources, especially if such connections entail role strain associated with obligations to provide social support to others. Third, egocentric networks are nested within a broader structure of social relationships. The notion of social capital embraces the embeddedness of individual social ties within the broader social structure. Fourth, despite some successes reported in social support interventions to enhance mental health, further work is needed to deepen our understanding of the design, timing, and dose of interventions that work, as well as the characteristics of individuals who benefit the most. (+info)
Prediction of peer-rated adult hostility from autonomy struggles in adolescent-family interactions.
Observed parent-adolescent autonomy struggles were assessed as potential predictors of the development of peer-rated hostility over a decade later in young adulthood in both normal and previously psychiatrically hospitalized groups of adolescents. Longitudinal, multireporter data were obtained by coding family interactions involving 83 adolescents and their parents at age 16 years and then obtaining ratings by close friends of adolescents' hostility at age 25 years. Fathers' behavior undermining adolescents' autonomy in interactions at age 16 years were predictive of adolescents-as-young-adults' hostility, as rated by close friends at age 25 years. These predictions contributed additional variance to understanding young adult hostility even after accounting for concurrent levels of adolescent hostility at age 16 years and paternal hostility at this age, each of which also significantly contributed to predicting future hostility. Results are discussed as highlighting a pathway by which difficulties attaining autonomy in adolescence may presage the development of long-term difficulties in social functioning. (+info)
Family adversity, positive peer relationships, and children's externalizing behavior: a longitudinal perspective on risk and resilience.
Peer acceptance and friendships were examined as moderators in the link between family adversity and child externalizing behavioral problems. Data on family adversity (i.e., ecological disadvantage, violent marital conflict, and harsh discipline) and child temperament and social information processing were collected during home visits from 585 families with 5-year-old children. Children's peer acceptance, friendship, and friends' aggressiveness were assessed with sociometric methods in kindergarten and grade 1. Teachers provided ratings of children's externalizing behavior problems in grade 2. Peer acceptance served as a moderator for all three measures of family adversity, and friendship served as a moderator for harsh discipline. Examination of regression slopes indicated that family adversity was not significantly associated with child externalizing behavior at high levels of positive peer relationships. These moderating effects generally were not qualified by child gender, ethnicity, or friends' aggressiveness, nor were they accounted for by child temperament or social information-processing patterns. The need for process-oriented studies of risk and protective factors is stressed. (+info)