[show abstract][hide abstract] ABSTRACT: Frequently a researcher is interested in a theoretical distribution or characteristics of that distribution, such as its mean, standard deviation, or 2.5 and 97.5 percentiles. One hundred or even 50 years ago, we were restricted practically by computing limitations to theoretical distributions that are described by an explicit equation, such as the binomial or multivariate normal distribution. Using mathematical models of distributions often requires considerable mathematical ability, and also imposes rather severe and often intractable assumptions on the applied researchers (e.g., normality, independence, variance assumptions, and so on). But computer simulations now provide more flexibility specifying distributions, which in turn provide more flexibility specifying models. One contemporary simulation technique is Markov chain Monte Carlo (MCMC) simulation, which can specify arbitrarily complex and nested multivariate distributions. It can even combine different theoretical families of variates. Another contemporary technique is the bootstrap, which can construct sampling distributions of conventional statistics that are free from most (but not all) assumptions. It can even create sampling distributions for new or exotic test statistics that the researcher created for a specific experiment
[show abstract][hide abstract] ABSTRACT: A quasi-experimental comparison of cousins differentially exposed to levels of neighborhood disadvantage (ND) was used with extensive measured covariates to test the hypothesis that neighborhood risk has independent effects on youth conduct problems (CPs). Multilevel analyses were based on mother-rated ND and both mother-reported CPs across 4-13 years (n = 7,077) and youth-reported CPs across 10-13 years (n = 4,524) from the Children of the National Longitudinal Survey of Youth. ND was robustly related to CPs reported by both informants when controlling for both measured risk factors that are correlated with ND and unmeasured confounds. These findings are consistent with the hypothesis that ND has influence on conduct problems.
Journal of Abnormal Psychology 09/2011; 121(1):95-108. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: The attack on the World Trade Center (WTC) on September 11, 2001, was an act of terrorism that had many potential influences on the city and state, including influences on families. We analyzed divorce data from 1991 to 2005 for all 62 New York counties to assess divorce response to the attack on the WTC. The results suggested that there were lower observed divorce rates in New York following the attack on the WTC than the prevailing 10-year cubic divorce trend would have predicted. We also compared counties in and around New York City to those farther away, and we compared metropolitan to nonmetropolitan counties in New York. In metropolitan counties, divorces were lower in the predicted direction.
Journal of Applied Social Psychology 07/2011; 41(7):1680 - 1700. · 0.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: Nonmaternal care of infant children is increasingly common, but there is disagreement as to whether it is harmful for children. Using data from 9,185 children (5 years and older) who participated in the Children of the National Longitudinal Survey of Youth, the current study compared 2 groups: those for whom nonmaternal care was initiated in the first 3 years and those for whom it was not. Between-family comparisons showed that early nonmaternal care was associated with higher achievement and lower behavior problem scores in childhood and adolescence. However, within-family comparisons failed to detect differences between siblings who had different early nonmaternal care experiences. The study concludes that the timing of entry to nonmaternal care in the first 3 years has neither positive nor negative effects on children's outcomes.
Child Development 06/2011; 82(4):1076-91. · 4.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: The authors review key features in the development of a successful PhD program delivered at a distance, including students, cohorts, teaching, curriculum, administrative structure, and current and future challenges.
New Directions for Adult and Continuing Education 03/2011; 2011(129):85 - 94.
[show abstract][hide abstract] ABSTRACT: Although the Flynn Effect has been studied widely across cultural, geographic, and intellectual domains, and many explanatory theories have been proposed, little past research attention has been paid to subgroup differences. Rodgers and Wänström (2007) identified an aggregate-level Flynn Effect (FE) at each age between 5 and 13 in the Children of the National Longitudinal Survey of Youth (NLSYC) PIAT-Math data. FE patterns were not obtained for Reading Recognition, Reading Comprehension, or Digit Span, consistent with past FE research suggesting a closer relationship to fluid intelligence measures of problem solving and analytic reasoning than to crystallized measures of verbal comprehension and memory. These prior findings suggest that the NLSYC data can be used as a natural laboratory to study more subtle FE patterns within various demographic subgroups. We test for subgroup Flynn Effect differences by gender, race/ethnicity, maternal education, household income, and urbanization. No subgroups differences emerged for three demographic categories. However, children with more educated (especially college educated) mothers and/or children born into higher income households had an accelerated Flynn effect in their PIAT-M scores compared to cohort peers with lower educated mothers or lower income households. We interpret both the positive and the null findings in relation to previous theoretical explanations.
[show abstract][hide abstract] ABSTRACT: In spite of long-held beliefs that traits related to reproductive success tend to become fixed by evolution with little or no genetic variation, there is now considerable evidence that the natural variation of fertility within populations is genetically influenced and that a portion of that influence is related to the motivational precursors to fertility. We conduct a two-stage analysis to examine these inferences in a time-ordered multivariate context. First, using data from the National Longitudinal Survey of Youth, 1979, and LISREL analysis, we develop a structural equation model in which five hypothesized motivational precursors to fertility, measured in 1979-1982, predict both a child-timing and a child-number outcome, measured in 2002. Second, having chosen two time-ordered sequences of six variables from the SEM to represent our phenotypic models, we use Mx to conduct both univariate and multivariate behavioral genetic analyses with the selected variables. Our results indicate that one or more genes acting within a gene network have additive effects that operate through child-number desires to affect both the timing of the next child born and the final number of children born, that one or more genes acting through a separate network may have additive effects operating through gender role attitudes to produce downstream effects on the two fertility outcomes, and that no genetic variance is associated with either child-timing intentions or educational intentions.
[show abstract][hide abstract] ABSTRACT: A quiet methodological revolution, a modeling revolution, has occurred over the past several decades, almost without discussion. In contrast, the 20th century ended with contentious argument over the utility of null hypothesis significance testing (NHST). The NHST controversy may have been at least partially irrelevant, because in certain ways the modeling revolution obviated the NHST argument. I begin with a history of NHST and modeling and their relation to one another. Next, I define and illustrate principles involved in developing and evaluating mathematical models. Following, I discuss the difference between using statistical procedures within a rule-based framework and building mathematical models from a scientific epistemology. Only the former is treated carefully in most psychology graduate training. The pedagogical implications of this imbalance and the revised pedagogy required to account for the modeling revolution are described. To conclude, I discuss how attention to modeling implies shifting statistical practice in certain progressive ways. The epistemological basis of statistics has moved away from being a set of procedures, applied mechanistically, and moved toward building and evaluating statistical and scientific models.
American Psychologist 01/2010; 65(1):1-12. · 6.87 Impact Factor
[show abstract][hide abstract] ABSTRACT: We examine how the motivational sequence that leads to childbearing predicts fertility outcomes across reproductive careers. Using a motivational traits-desires-intentions theoretical framework, we test a structural equation model using prospective male and female data from the National Longitudinal Survey of Youth. Specifically, we take motivational data collected during the 1979-1982 period, when the youths were in their teens and early twenties, to predict the timing of the next child born after 1982 and the total number of children born by 2002. Separate models were estimated for males and females but ivith equality constraints imposed unless relaxing these constraints improved the overall model fit. The results indicate substantial explanatory power of fertility motivations for both short-term and long-term fertility outcomes. They also reveal the effects of both gender role attitude and educational intentions on these outcomes. Although some gender differences in model pathways occurred, the primary hypothesized pathways were essentially the same across the genders. Two validity substudies support the soundness of the results. A third sub-study comparing the male and female models across the sample split on the basis of previous childbearing revealed a number of pattern differences within the four gender-by-previous childbearing groups. Several of the more robust of these pattern differences offer interesting insights and support the validity and usefulness of our theoretical framework.
Biodemography and Social Biology 01/2010; 56(1):1-23. · 1.37 Impact Factor
[show abstract][hide abstract] ABSTRACT: It is necessary to determine if causal influences on developing antisocial behavior change with age to guide both research and theory on its origins. The extent to which the same genetic factors influence antisocial behavior across 4-17 years of age was estimated using 2,482 sibling pairs of varying genetic relatedness. Assessments of antisocial behavior by mothers (4-9 years), mothers and youth (10-13 years), and youth (14-17 years) reflected the changing validity of informants across development. Genetic influences on antisocial behavior at 14-17 years were entirely shared with those on antisocial behavior at 10-13 years according to both informants. Genetic influences on antisocial behavior at 14-17 years were distinct from those at 4-9 years, however. These age differences in genetic influences cannot be fully distinguished from informant differences across age, but the present findings indicate that youth reported to be persistently antisocial during childhood and adolescence are influenced by one set of genetic factors influencing parent-report conduct problems in childhood and a second set of genetic influences on youth-reported delinquency that come into play around the time of the pubertal transition.
Journal of Abnormal Psychology 11/2009; 118(4):711-21. · 4.86 Impact Factor
[show abstract][hide abstract] ABSTRACT: Children raised without a biological father in the household have earlier average ages of first sexual intercourse than children raised in father-present households. Competing theoretical perspectives have attributed this either to effects of father absence on socialization and physical maturation or to nonrandom selection of children predisposed for early sexual intercourse into father-absent households. Genetically informative analyses of the children of sister dyads (N = 1,382, aged 14-21 years) support the selection hypothesis: This association seems attributable to confounded risks, most likely genetic in origin, which correlated both with likelihood of father absence and early sexual behavior. This holds implications for environmental theories of maturation and suggests that previous research may have inadvertently overestimated the role of family structure in reproductive maturation.
Child Development 08/2009; 80(5):1463-80. · 4.92 Impact Factor
[show abstract][hide abstract] ABSTRACT: Resampling is a statistical approach that relies on empirical analysis, based on the observed data, instead of asymptotic and parametric theory. The goal of resampling is to make an inferential decision, which is the same goal as that of a parametric statistical test such as the conventional t or ANOVA. The difference is in how the goal is achieved.
In this chapter, we will define and describe three resampling procedures: the permutation test, the jackknife and the bootstrap. We place a strong emphasis on the bootstrap because it is the most flexible and most frequently used. We will describe both the concepts and the mechanisms that underlie resampling theory. In the course of this development, we hope that readers new to this area will begin to see ways of incorporating resampling methods into various aspects of their applied research, ways that allow them to address novel questions that traditional parametric approaches cannot easily address. We also hope that practicing methodologists as well will find new applications for resampling methods, and appropriate appreciation for their flexibility and overall value (as well as their limitations).
[show abstract][hide abstract] ABSTRACT: Theoretical models concerning how neighborhood contexts adversely influence juvenile antisocial behavior frequently focus on urban neighborhoods; however, previous studies comparing urban and rural areas on the prevalence of youth antisocial behavior have yielded mixed results. The current study uses longitudinal data on the offspring of a nationally representative sample of mothers (N = 4,886) in the US. There was no relation between density and mother-reported child conduct problems across ages 4-13 years, but youth living in areas of greater population density exhibited more youth self-reported delinquency across 10-17 years. Families often moved to counties with greater or lesser population density, but longitudinal analyses treating population density as a time-varying covariate did not support the hypothesis that living in densely populated counties influenced youth delinquency. Rather, the association between population density and delinquency appears to be due to unmeasured selection variables that differ between families who live in more or less densely populated counties.
Journal of Child Psychology and Psychiatry 04/2009; 50(8):999-1008. · 5.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Recent studies suggest that the association between maternal age at childbearing (MAC) and children's disruptive behaviors is the result of family factors that are confounded with both variables, rather than a casual effect of environmental factors specifically related to MAC. These studies, however, relied on restricted samples and did not use the strongest approach to test causal influences.
Using data on 9,171 4-9-year-old and 6,592 10-13-year-old offspring of women from a nationally representative sample of US households, we conducted sibling-comparison analyses. The analyses ruled out all genetic factors that could confound the association, as well as all environmental confounds that differ between unrelated nuclear families, providing a strong test of the causal hypothesis that the environments of children born at different maternal ages influence mother- and self-reported disruptive behaviors.
When these genetic and environmental confounds were ruled out as alternative explanations, the relation between environments within nuclear families specifically associated with MAC and disruptive behaviors was robust, with the association being stronger for second- and third-born children.
Environmental factors specifically associated with early MAC within nuclear families account for increased risk of offspring disruptive behaviors, especially in later-born children.
Journal of Child Psychology and Psychiatry 04/2009; 50(8):1018-28. · 5.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Inattentive-hyperactive and oppositional behavior have been hypothesized to be developmental precursors to conduct problems. We tested these hypotheses using a longitudinal sample of 6,466 offspring of women selected from nationally representative US households. Conduct problems across 8-13 years were robustly predicted by conduct problems at 4-7 years, but also were independently predicted to a small extent by both inattentive-hyperactive and oppositional behaviors at 4-7 years. Longitudinal multivariate behavior genetic analyses revealed that the genetic and environmental factors that influence conduct problems at both 4-7 and 8-13 years also influence the putative precursors at 4-7 years. After genetic and environmental influences on conduct problems at 4-7 years were taken into account, however, inattentive-hyperactive and oppositional behavior at 4-7 years shared causal influences with conduct problems 8-13 years to a negligible extent. These findings suggest that after early conduct problems are controlled, little is gained in terms of prediction or understanding genetic and environmental influences on later child conduct problems by treating early inattentive-hyperactive and oppositional behavior as developmental precursors to later conduct problems.
[show abstract][hide abstract] ABSTRACT: The study presents a quasi-experimental analysis of data on 9,194 offspring (ages 4-11 years old) of women from a nationally representative U.S. sample of households to test the causal hypotheses about the association between family income and childhood conduct problems (CPs). Comparison of unrelated individuals in the sample indicated a robust inverse association, with the relation being larger at higher levels of income and for male offspring, even when statistical covariates were included to account for measured confounds that distinguish different families. Offspring also were compared to their siblings and cousins who were exposed to different levels of family income in childhood to rule out unmeasured environmental and genetic factors confounded with family income as explanations for the association. In these within-family analyses, boys exposed to lower family income still exhibited significantly higher levels of CPs. When considered in the context of previous studies using different designs, these results support the inference that family income influences CPs, particularly in males, through causal environmental processes specifically related to earnings within the nuclear family.