Rank correlation plots for use with correlated input variables

A method for inducing a desired rank correlation matrix on multivariate input vectors for simulation studies has recently been developed by Iman and Conover (1982). The primary intention of this procedure is to produce correlated input variables for use with computer models. Since this procedure is distribution free and allows the exact marginal distributions to remain intact it can be used with any marginal distributions for which it is reasonable to think in terms of correlation. In this paper we present a series of rank correlation plots based on this procedure when the marginal distributions are normal, lognormal, uniform and loguniform. These plots provide a convenient tool both for aiding the modeler in determining the degree of dependence among input variables (rather than guessing) and for communicating with the modeler the effect of different correlation assumptions. In addition this procedure can be used with sample multivariate data by sampling directly from the respective marginal empirical distribution functions.     

A Note on Breiman's Random Forest Data Mining Technique and Conventional Cox Modeling of Survival Statistics: The Case of the Phantom “Induct” Covariate in the Ohio State University Kidney Transplant Database

This note represents a portion of the research that has been conducted using the Ohio State University's large kidney transplant database. Our latest results into understanding the impact of covariates on renal graft success including the impact of drug therapy are discussed.

The major result here is that using both the Cox model and Breiman's Random Forest Data Mining techniques has helped to unravel the mystery of the “induct” immunosuppressant covariate slipping in and out of the list of important variables. We also make the interesting observation that the Random Forest method seems to mimic the clinician's (R.P.) understanding of the importance of variables.     

An Evaluation of Major League Baseball Offensive Performance Models

Numerous statistics have been proposed to evaluate offensive performance in baseball. Each statistic or estimator can be related to an explicit run production model. An evaluation of ten run production models is presented based on major league team run production in the period 1969–1976. The results are applied to evaluating individual players in both the American and National baseball leagues.     

The effects of welfare and child support policies on union formation

We use data from a new longitudinal survey – the Fragile Families and Child Wellbeing Study – to examine how welfare and child support policies, and local labor market conditions, affect union formation among unmarried parents who have just had a child together. We use multinomial logistic regression to estimate the effects of the policy variables along with economic, cultural/interpersonal, and other factors on whether (relative to being in a cohabiting relationship) parents are not romantically involved, romantically involved living apart, or married to each other about one year after the child's birth. We find that – contrary to some previous research – higher welfare benefits discourage couples from breaking up, while strong child support enforcement reduces the chances that unmarried parents will marry; local unemployment rates do not appear to be strongly associated with union formation decisions after a nonmarital birth.     

Kinship Support,Family Relations,and Psychological Adjustment Among Low‐Income African American Mothers and Adolescents

The association of kin social support with mothers' adjustment and family relations was assessed among 204 African American mothers and adolescents who were on average 14.45 years of age. Also examined was the association of mothers' adjustment with family relations and adolescents' adjustment. Findings revealed that kin social and emotional support was positively associated with mothers' optimism. Poor relations with kin were positively associated with mothers' depression. Kin advice and counseling and kin social and emotional support were positively linked to family routine. Poor relations with kin were positively associated with parent/adolescent communication problems. Mothers' optimism was positively associated with family routine and mediated the association of kin social and emotional support with family routine. Parent/adolescent communication problems were positively associated with adolescents' depression. The findings were discussed in light of their support for theoretical and empirical work on family processes among poor African American families.     

Adolescent Fathers' Parenting Stress,Social Support,and Involvement with Infants

The present study examined the relationship between concurrent measures of adolescent fathers' parenting stress, social support, and fathers' care‐giving involvement with the 3‐month‐old infant, controlling for fathers' prenatal involvement. The study sample consisted of 50 teenage father–mother dyads. Findings from multivariate regression revealed that fathers' parenting stress was significantly and negatively related to fathers' care giving as perceived by both fathers and mothers. The relationship between support for father involvement provided by the young man's parents and father reported care‐giving involvement approached significance. Social support from both teenagers' parents buffered the negative influence of parenting stress on fathers' involvement with the baby. Policy and intervention implications are discussed.     

RELATIONAL SCHEMAS, HOSTILE ROMANTIC RELATIONSHIPS, AND BELIEFS ABOUT MARRIAGE AMONG YOUNG AFRICAN AMERICAN ADULTS

The present study tests a developmental model designed to explain the romantic relationship difficulties and reluctance to marry often reported for African Americans. Using longitudinal data from a sample of approximately 400 African American young adults, we examine the manner in which race-related adverse experiences during late childhood and early adolescence give rise to the cynical view of romantic partners and marriage held by many young African Americans. Our results indicate that adverse circumstances disproportionately suffered by African American youth (viz., harsh parenting, family instability, discrimination, criminal victimization, and financial hardship) promote distrustful relational schemas that lead to troubled dating relationships, and that these negative relationship experiences, in turn, encourage a less positive view of marriage.     

Double Jeopardy: Work Ethic Differences in Youth at Risk of School Failure

The purpose of this study was to determine if work ethic differed for a sample of 152 selected 9th-grade students categorized by risk of school failure and by gender. Work ethic attributes were measured using the Occupational Work Ethic Inventory (Petty, 1993). Results of a two-way multivariate analysis of variance indicated significant work ethic differences in main effects of at-risk classification and gender for dependent variables of interpersonal skills, initiative, and being dependable. Interaction effects were not significant. Underlying constructs indicated that adolescents with greater degrees of risk were less dependable and that girls in the study were more dependable than boys.