Probabilities for separating sets of order statistics

Consider a set of order statistics that arise from sorting samples from two different populations, each with their own, possibly different distribution functions. The probability that these order statistics fall in disjoint, ordered intervals and that of the smallest statistics, a certain number come from the first populations is given in terms of the two distribution functions. The result is applied to computing the joint probability of the number of rejections and the number of false rejections for the Benjamini-Hochberg false discovery rate procedure.     

Tenancy,Marriage, and the Boll Weevil Infestation, 1892–1930

In the early twentieth century, the cotton-growing regions of the U.S. South were dominated by families of tenant farmers. Tenant farming created opportunities and incentives for prospective tenants to marry at young ages. These opportunities and incentives especially affected African Americans, who had few alternatives to working as tenants. Using complete-count Census of Population data from 1900–1930 and Census of Agriculture data from 1889–1929, we find that increases in tenancy over time increased the prevalence of marriage among young African Americans. We then study how marriage was affected by one of the most notorious disruptions to southern agriculture at the turn of the century: the boll weevil infestation of 1892–1922. Using historical Department of Agriculture maps, we show that the boll weevil’s arrival reduced the share of farms worked by tenants as well as the share of African Americans who married at young ages. When the boll weevil infestation altered African Americans’ opportunities and incentives to marry, the share of African Americans who married young fell accordingly. Our results provide new evidence about the effect of economic and political institutions on demographic transformations.     

Expected Power for the False Discovery Rate with Independence

The Benjamini–Hochberg procedure is widely used in multiple comparisons. Previous power results for this procedure have been based on simulations. This article produces theoretical expressions for expected power. To derive them, we make assumptions about the number of hypotheses being tested, which null hypotheses are true, which are false, and the distributions of the test statistics under each null and alternative. We use these assumptions to derive bounds for multiple dimensional rejection regions. With these bounds and a permanent based representation of the joint density function of the largest p-values, we use the law of total probability to derive the distribution of the total number of rejections. We derive the joint distribution of the total number of rejections and the number of rejections when the null hypothesis is true. We give an analytic expression for the expected power for a false discovery rate procedure that assumes the hypotheses are independent.     

Participation in Voluntary Youth‐Serving Associations and Early Adult Voting Behavior*

Objective. We investigate adolescent membership in voluntary associations and whether participation in these activities influences voting behavior during early adulthood. Methods. Weighted logistic regression models predicting membership in voluntary associations and voting behavior were estimated using data from the National Educational Longitudinal Study of 1988–1994 (NELS). Results. Our findings suggest that membership in voluntary associations varies by race and socioeconomic status (SES). In addition, membership in organizations historically rooted in moral development and civic socialization positively predict voter‐registration status and whether or not young adults participated in the first national election that they were eligible to vote in, but this relationship is moderated by both race and SES. Conclusions. Our findings suggest that a large proportion of U.S. teenagers still participate in community‐based programs, many of which foster later civic participation, but that all youth do not equally benefit from participation.     

Introduction: Globalisation and identity

Abstract

This paper examines the identities of early leaders of the African National Congress (ANC) at a time when British influences still prevailed in South Africa. African attitudes to the “British World” reveal complex identities that also reflected political and cultural variations according to race, class and region. Relations between ANC leaders and the African “elite” and between the elite and subaltern strata were not straightforward. A careful reading of the discourses in and around Congress points to contradictory attitudes to things British and to ambiguous identities that lingered and contributed to the mix of social and national ideas and identities that influence contemporary South Africa.     

Body mass index, academic achievement, and school context: examining the educational experiences of adolescents at risk of obesity

Reflected self-appraisal suggests that individual functioning is related to the fit between individual characteristics and the norms of their primary contexts. To apply this social psychological concept to the study of obesity, we hypothesized that adolescents at risk of obesity would have lower academic achievement overall than other students, especially in schools in which their weight status was most likely to elicit negative evaluations. Multi-level modeling of nationally representative data revealed that the negative longitudinal association between risk of obesity and achievement was stronger in schools with higher rates of romantic activity and lower average body size among students, two school contexts in which obesity was likely to be stigmatized, but weaker in schools with higher rates of athletic participation, a school context in which such stigmatization was also likely. Additional analyses suggested that this last, unexpected finding reflected a process of niche-picking.     

Reputation, trust and the dynamics of leadership in communities of practice

The aim of this article is to propose a theoretical framework describing the internal organization of communities of practice in a dynamic perspective. More precisely, we argue that communities of practice adopt some specific patterns of internal organization where some of their members obtain a leadership status. Leaders contribute to cognitive advance of the community of practice by providing members with a consistent and coherent vision of its objectives. We identify two of their attributes as important for allowing them to fulfil their task: informational mimesis and mediation. Finally, we propose a simulation model describing the emergence of leadership as the outcome of a self-organizing process. We find that leaders correspond to members who are characterized by higher levels of activity in the community.This work has greatly benefited from comments by participants at the 3^rd ETE Workshop held in Sophia-Antipolis. Comments by Markus Becker, Antoine Bureth, Patrick Cohendet, Robin Cowan, Christophe Lerch, Julien Pénin are gratefully acknowledged. Remarks by two anonymous reviewers and the editor contributed to improve significantly the quality of the article. The usual disclaimer applies.     

On the distribution of summary statistics for missing data

Under an assumption that missing values occur randomly in a matrix, formulae are developed for the expected value and variance of six statistics that summarize the number and location of the missing values. For a seventh statistic, a regression model based on simulated data yields an estimate of the expected value. The results can be used in the development of methods to control the Type I error and approximate power and sample size for multilevel and longitudinal studies with missing data.