Combining least-squares and quantile regressions

Least-squares and quantile regressions are method of moments techniques that are typically used in isolation. A leading example where efficiency may be gained by combining least-squares and quantile regressions is one where some information on the error quantiles is available but the error distribution cannot be fully specified. This estimation problem may be cast in terms of solving an over-determined estimating equation (EE) system for which the generalized method of moments (GMM) and empirical likelihood (EL) are approaches of recognized importance. The major difficulty with implementing these techniques here is that the EEs associated with the quantiles are non-differentiable. In this paper, we develop a kernel-based smoothing technique for non-smooth EEs, and derive the asymptotic properties of the GMM and maximum smoothed EL (MSEL) estimators based on the smoothed EEs. Via a simulation study, we investigate the finite sample properties of the GMM and MSEL estimators that combine least-squares and quantile moment relationships. Applications to real datasets are also considered.     

A course for clinical trial personnel in clinical study designs, randomization, allocation schedules, and interactive response systems

This continuing education course for professionals involved in all areas of clinical trials integrates concepts related to the role of randomization in the scientific process. The course includes two interactive lecture and discussion sections and a workshop practicum. The first interactive lecture introduces basic clinical trial issues and statistical principles such as bias, blinding, randomization, control groups, and the importance of formulating clear and discriminating clinical and statistical hypotheses. It then focuses on the most commonly used clinical study designs and the corresponding patient randomization schemes. The second interactive lecture focuses on the implementation of randomization of patients and drug supply through allocation and component ID schedules. The workshop practicum, conducted in small groups, enables students to apply the lecture concepts to real clinical studies. Flexibility was built into the workshop practicum materials to allow the course content to be customized to specific audiences, and the interactive lecture sessions can be stretched to cover more advanced topics according to class interest and time availability.     

Dynamics of adolescent friendship networks and smoking behavior

The mutual influence of smoking behavior and friendships in adolescence is studied. It is attempted to disentangle influence and selection processes in reciprocal and non-reciprocal friendships. An actor-based model is described for the co-evolution of friendship networks and smoking behavior. This model considers alternative selection and influence mechanisms, and models continuous-time changes in network and behavior. The data consists of a longitudinal sample of 1326 Finnish adolescents in 11 high schools. Findings suggest that selection as well as influence processes play an important role in adolescent smoking behavior. Selection had a relatively stronger role than influence, in particular when selecting non-reciprocal friends. The strength of both influence and selection processes decreased over time.     

Entrepreneurs and producers: Identities of Finnish farmers in 2001 and 2006

The farmers' role within the EU has recently been under reconstruction: in addition to primary agricultural production farmers should fulfil multiple functions such as maintaining the rural landscape, conserving nature and providing services. One essential feature of this new role is the demand for entrepreneurship. Farmers should be capable of competing in the worldwide, global agricultural market. They are also encouraged to diversify into business activities beyond agriculture. How do farmers see themselves in this situation? Is their self-perception compatible with this new reconstruction of the farming economy and the farmers' role? Research, thus far, seems to indicate that traditional or production oriented identities are still dominant among farmers. But there is also some evidence that new identities, such as the entrepreneurial identity, are emerging. In our study we are especially interested in how Finnish farmers have met the demand for adapting to the role of an entrepreneur. We approach the issue of the farmers' changing role from a social psychological perspective by utilizing the concept of identity. Our empirical evidence comes from two nation-wide postal questionnaire data sets, both containing samples from three subgroups: conventional farmers focusing solely on primary agricultural production, diversified farmers who also had other business besides agricultural production, and rural non-agricultural small-scale businesses. The results show that Finnish farmers do not experience “entrepreneur” as something distant from themselves and as not fitting in with their world of ideas, as the work of some researchers would depict. Instead, the majority of Finnish farmers, especially diversified farmers, conceive of themselves both as entrepreneurs and as producers.     

Depression, anxiety, and religious life: a search for mediators

We examine several potential mechanisms linking religious involvement to depressive symptoms, major depression, and anxiety. Logistic and OLS regression estimations test five sets of potential psychosocial religion mediators: perceived attitudes toward and motivations for attendance; positive and negative religious coping; religious attitudes, beliefs, and spirituality; congregational support and criticism; and interpersonal and self-forgiveness. Compared to attending services less than once a month or never, attending services once a week but no more is associated with fewer depressive symptoms and anxiety symptoms. Hypothesized mediators, including meaning, interpersonal and self-forgiveness, congregational criticism, social attendance beliefs, and negative coping are independently associated with one or more mental health outcomes.     

Family and Household Formations and Suicide in the United States

Family support systems have been theoretically linked to suicide risk. But no research to date has investigated the effects of detailed living arrangements on individual risk of suicide. Using data on 825,462 adults from the National Health Interview Survey Linked Mortality File reveals that living in families with stronger sources of social support and integration decreases risk of suicide. These effects persist despite controls for important individual level characteristics. Risk of suicide decreases for persons in married as well as unmarried families when children are present and risk increases for persons living with unrelated adults. These results reveal the structural importance of family formation on the social integrative forces that contribute to an individual's risk of suicide.     

Preventing child abuse and neglect: a national evaluation of Parents Anonymous groups

This evaluation assessed whether participation in Parents Anonymous mutual support groups was associated with child maltreatment prevention. Parents new to groups across the United States were interviewed at baseline, one month, and six months. Using standardized scales, all parents showed improvements in some child maltreatment outcomes, risk factors, and protective factors. Parents starting out with particularly serious needs showed statistically significant improvement on every scale. Results indicated that Parents Anonymous participation contributes to child maltreatment reduction.     

Leaving Chicago for Iowa's "Fields of Opportunity": Community Dispossession, Rootlessness, and the Quest for Somewhere to "Be OK"

In recent years, urban development and public housing demolition have posed challenges to the social and geographic rootedness of low-income African Americans in urban areas. In particular, in Chicago, widespread public housing demolition, occurring in the context of rapid gentrification, has contributed to increasing shortages of affordable low-income housing. This study uses in-depth interviews and participant observation to examine the migration experiences of men and women who have left urban neighborhoods and public housing developments in Chicago searching for affordable housing and economic opportunity in eastern Iowa. This particular analysis focuses on experiences of social and geographic "rootlessness" that emerged as a major theme in these interviews. Participants describe community dispossession in Chicago that has threatened not only the ties between individuals and their social support networks, but also connections and claims to the places in which these ties are rooted. Narratives that describe leaving Chicago in this context and then trying to get by as a stigmatized outsider in "someone else's city" speak to a process of dislocation that may disrupt critical social-support resources that are known to mitigate the consequences of structural disadvantage.