The power of the exponential scores test for an ordinary renewal process against trend alternatives

The power properties of a statistic based on the use of exponential scores which may be used for testing whether a series of events occurring in time form an ordinary renewal process against trend alternatives are examined. Small sample power comparisons under a Lehmann trend alternative are made with an alternative nonparametric test based on a rank trend statistic and with the parametric test when the intervals are exponentially distributed. Finally, some asymptotic efficiency results are developed for limiting trend alternatives.     

Social Capital,Labour Markets,and Job‐Finding in Urban and Rural Regions: comparing paths to employment in prosperous cities and stressed rural communities in Canada1,2

This paper compares paths to employment (job‐finding) in prosperous cities and economically‐stressed rural communities in Canada. Since the pioneering work of Mark Granovetter (1973; 1974 ), sociologists have investigated the role of social capital in job‐finding (specifically, the use of strong and weak social ties to find out about employment opportunities). To date, however, there have been few direct comparisons of job‐finding in urban and rural settings (see Lindsay et al., 2005 ; Wahba and Zenou, 2005 ). Using data from two major surveys and a qualitative interview project, we uncover several important differences in urban and rural paths to employment. First, we find that both strong and weak ties are used more frequently by rural residents to find a job, while city‐dwellers rely more often on formal or impersonal means. Second, we find much stronger evidence of differentiation within rural regions. Long‐time rural residents are much more likely to use strong and weak ties to find employment than are newcomers. However, rural residents who used weak ties as paths to employment have significantly lower incomes. None of these patterns are evident in the cities. Together, these findings lead us to conclude that job‐finding in rural settings is strongly affected by constraints – in the labour market and in social capital resources – that are not present in cities.     

Could “Acculturation” Effects Be Explained by Latent Health Disadvantages Among Mexican Immigrants?

This paper tests portions of a new theory of immigrant health by focusing exclusively on latent biomarkers of future health risks. Using data from the National Health and Nutrition Examination Survey III, 1988–1994 – we uncover the typically observed immigrant health advantage among recent immigrants that diminishes among long‐term immigrants. In addition, we observe worse health among U.S.‐born Mexican Americans relative to non‐Hispanic Whites. Finally, although our theory suggests that recent immigrants may have latent health risks due to disadvantaged childhood experiences, we do not find evidence in support of this theory.     

The stability of exchange networks

Economic and sociological exchange theories predict divisions of exchange benefits given an assumed fixed network of exchange relations. Since network structure has been found to have a large impact on actors’ payoffs, actors have strong incentives for network change. We answer the question what happens to both the network structure and actor payoffs when myopic actors change their links in order to maximize their payoffs. We investigate the networks that are stable, the networks that are efficient or egalitarian with varying tie costs, and the occurrence of social dilemmas. Only few networks are stable over a wide range of tie costs, and all of them can be divided into two types: efficient networks consisting of only dyads and at most one isolate, and Pareto efficient and egalitarian cycles with an odd number of actors. Social dilemmas are observed in even-sized networks at low tie costs.     

Racemaking in New Orleans: racial boundary construction among ideologically diverse college students

We explore how an ideologically diverse group of white students at Tulane University respond to evidence of racial inequality in post-Katrina New Orleans. In line with prior research, we find commonalities in racialized attitudes and behaviours between students whose racial ideologies otherwise differ. Drawing from anthropological theories of boundary construction and sociological work on colour-blind racism, we argue that the Otherization of non-whites is part of the everyday worldviews and social practices of white Americans. We draw on fieldwork in New Orleans to demonstrate that racist stereotypes and beliefs in racial difference continue to be transmitted within white social spaces. We find that even the most progressive Tulane students are engaged in the construction and reinforcement of symbolic and spatial boundaries between themselves and African Americans. This achieves the purpose for which racial stereotypes were originally constructed – namely, the persistence of racial inequality.     

Parameter estimation for mixtures of skew Laplace normal distributions and application in mixture regression modeling

In this article, we propose mixtures of skew Laplace normal (SLN) distributions to model both skewness and heavy-tailedness in the neous data set as an alternative to mixtures of skew Student-t-normal (STN) distributions. We give the expectation–maximization (EM) algorithm to obtain the maximum likelihood (ML) estimators for the parameters of interest. We also analyze the mixture regression model based on the SLN distribution and provide the ML estimators of the parameters using the EM algorithm. The performance of the proposed mixture model is illustrated by a simulation study and two real data examples.     

Promoting Career and College Readiness,Aspirations, and Self‐Efficacy: Curriculum Field Test

To address the need for enhanced career and college readiness, a classroom guidance curriculum was studied using a pretest–posttest nonequivalent groups quasi‐experimental design. Data from 163 ninth‐grade students enrolled in a low‐performing high school were analyzed via hierarchical linear modeling. The analyses indicated a treatment effect on postsecondary education‐going knowledge and career and college readiness self‐efficacy, accounting for 100% of the variance explained by classroom‐level factors and indicating potential for the classroom guidance curriculum. The findings encourage career and professional school counselors to proactively employ similar classroom guidance programs aimed at encouraging high school students to consider postsecondary education opportunities. Future research could focus on component analyses of the curriculum, broadening the target populations, using mixed‐method designs, and additional validity studies of the dependent measures.     

A modified Friedman test for randomized complete block designs

The Friedman test is often used for a randomized complete block design when the normality assumption is not satisfied or the data are ordinal. The Friedman test can be viewed as an extension of the sign test for multiple measurements within each subject or block. We propose a modified Friedman test based on the Wilcoxon sign rank approach. Coincidentally, Tukey proposed a test statistic similar to our proposed test, but blocks are ranked by the minimum difference within each block. In the proposed test, we use the variance of block to rank the blocks, with the least variance being ranked the smallest. In both Tukey test and the modified Friedman test, linear ranks are used for blocks and treatments. The Tukey test belongs to the family of weighted-ranking test from Quade (1979 Quade, D. (1979). Using weighted rankings in the analysis of complete blocks with additive block effects. Journal of the American Statistical Association 74(367):680–683. [Google Scholar]).The modified Friedman test, the Friedman test and the Tukey test are compared under various conditions and the results indicate that the proposed test is generally more powerful than the Friedman test and the Tukey test when the number of groups is small.     

Adaptive LASSO for linear regression models with ARMA-GARCH errors

The linear regression models with the autoregressive moving average (ARMA) errors (REGARMA models) are often considered, in order to reflect a serial correlation among observations. In this article, we focus on an adaptive least absolute shrinkage and selection operator (LASSO) (ALASSO) method for the variable selection of the REGARMA models and extend it to the linear regression models with the ARMA-generalized autoregressive conditional heteroskedasticity (ARMA-GARCH) errors (REGARMA-GARCH models). This attempt is an extension of the existing ALASSO method for the linear regression models with the AR errors (REGAR models) proposed by Wang et al. in 2007 Wang, H., Li, G., Tsai, C. (2007). Regression coefficient and autoregressive order shrinkage and selection via the lasso. Journal of the Royal Statistical Society: Series B 69:63–78. [Google Scholar]. New ALASSO algorithms are proposed to determine important predictors for the REGARMA and REGARMA-GARCH models. Finally, we provide the simulation results and real data analysis to illustrate our findings.     

Comparison of unweighted and weighted rank based tests for an ordered alternative in randomized complete block designs

In randomized complete block designs, a monotonic relationship among treatment groups may already be established from prior information, e.g., a study with different dose levels of a drug. The test statistic developed by Page and another from Jonckheere and Terpstra are two unweighted rank based tests used to detect ordered alternatives when the assumptions in the traditional two-way analysis of variance are not satisfied. We consider a new weighted rank based test by utilizing a weight for each subject based on the sample variance in computing the new test statistic. The new weighted rank based test is compared with the two commonly used unweighted tests with regard to power under various conditions. The weighted test is generally more powerful than the two unweighted tests when the number of treatment groups is small to moderate.