Longitudinal analysis of friendship networks

This note discusses and demonstrates methods, both exploratory and confirmatory, for analysing data from friendship networks collected over time. The focus is on stochastic models for dyadic interaction designed to quantify the structural effect of reciprocity on arc changes. The networks studied were previously analysed by Hallinan (Social Networks 1: 193–210) who was concerned with stability of dyadic choices and the direction of change of asymmetric dyads to either mutual or null dyads. These aspects of the networks are really of secondary importance to the effect of reciprocated choices on the probabilities of dyadic change. Measures of this ‘reciprocity effect’ are presented, and comments on the rationale for continuous-time Markov chains as models for networks are given.     

What do effective teachers of inner-city children have in common?

This paper investigates the extent to which variables describing the classroom behavior of teachers and variables describing teachers' backgrounds and training explain differences in the effectiveness of teachers in improving the vocabulary skills of inner-city black children in four elementary grade levels. The results indicate that both types of variables explain significant portions of the variation in student achievement. In other words, teachers' choices of techniques matter; and the characteristics of teachers provide some information about their effectiveness. However, the pattern of results indicates that great care must be taken in interpreting individual coefficients. The paper concludes with an interpretation of the results and with suggestions for new directions for research on teaching that follow from this interpretation.     

Tracing developmental trends in Ira Gordon's programs for children and families

Ira Gordon's work in the area of child and family services is traced for six of his programs according to two main trends: (1) perceptions of families through the years and the changing roles of parents in the education of their children; and (2) curriculum changes in activities brought into homes. Gordon's programs, some being initiated as early as 1966, focused upon parents, infants, toddlers, and school-age children and utilized home visitations as a major intervention strategy. Evidence of successes reported for these programs has shown the impact of early intervention upon children as well as their families, school, and community.     

Being Under Pressure to Sext: Adolescents' Experiences,Reactions, and Counter-Strategies

This study explored adolescents' experiences of being under pressure to sext (sending nude images), offering insights into what situations adolescents view as pressuring, how adolescents react to the pressure, and what counter-strategies they use. Written statements from 225 adolescents (age 13–16 years, M = 14.4 years, SD = 0.93) were analyzed using thematic analysis. Results indicated a range of situations including both explicit and implicit pressure. The pressure elicited different emotional responses, including severe physical and psychological reactions, becoming distressed, and being seemingly unconcerned. A majority of the adolescents reported successful strategies on how to ward off the unwanted sexual requests. This study provides insight into how young people cope with potentially harmful situations online.     

Recursive models for categorical data

Standard methods for recursive models with continuous endogenous variables are extended to models with categorical endogenous variables. The concept of a reduced-form equation is generalized in a natural way to cover nonlinear regression functions and, in particular, models with categorical endogenous variables. Maximum-likelihood estimation and asymptotic chi-square tests are described. Two numerical examples are presented: a linear recursive two-equation model for all-categorical data, and a combined linear and logit three-equation recursive model with both categorical and continuous endogenous variables. Limitations of the present work and directions for further extension are noted.     

动态需求下车辆路径问题的周期性优化模型及求解

针对客户点不断更新的动态需求车辆路径问题,依据滚动时域对配送中心工作时间进行划分,提出基于延迟服务的周期性客户点实时重置策略,策略中延迟服务机制能结合车辆启动延迟系数对照当前时域的时间进行检验,满足所有客户点的服务需求,保证车辆满足中心时间窗约束。设计多阶段求解的混合变邻域人工蜂群算法对各时间片内子问题进行连续迭代优化,算法中子路径动态转变的设计能较好平衡原有客户点和新客户点对路径更新和车辆实时信息匹配的要求。算例验证及对比分析表明本文策略和算法在求解动态问题时的有效性和可行性。     

走出几个误区树立正确的学生观

受应试教育的影响 ,在中小学教育中 ,有些人在学生观上存在着几个误区 ,认为学生要服从教师 ,好学生太少了 ,学生都是有缺点的 ,学生不会学习等。这些误区的存在各有其思想根源 ,又都不符合时代的需要 ,不利于学生的发展。当前的教育改革 ,要采取切实可行的措施 ,走出这些误区 ,树立正确的学生观     

Bringing the cops back in: A study of efforts to make the criminal justice system more responsive to incidents of family violence

This paper examines the ways in which the criminal justice system typically responds to incidents of violence between adult members of the same household and then using a three equation, nonrecursive time series model considers the impact of efforts in one locale to improve law enforcement practices. Three questions are addressed: (a) can the apparent underreporting of domestic violence by police be improved; (b) can the quality of information funneled from police to the District Attorney's office be enhanced; and (c) can the number of offenders held accountable for their actions be increased?     

Constructing simple theories from propositional inventories

For better or worse, vast amounts of the research in the social sciences is done by researchers working independently of each other. Moreover, until quite recently, most of the data gathered has been of the correlational variety, relating two variables at a time. Consequently, those who try to make theoretical sense out of the vast amount of data often give up this task as hopeless.One way of alleviating this situation is through a propositional inventory: by bringing into one volume a large number of propositions that cover similar grounds. The late 1950s and the 1960s saw an upsurge in such inventories and this trend has continued into the 1970s.¹ Yet even these inventories do not condense and organize the data sufficiently to permit one to develop theories from them. In this paper we shall describe and illustrate a procedure which permits one to construct simple theories from propositional inventories.