Biomedical subjects

Michael T Willoughby

Publications and source records attributed to Michael T Willoughby.

3 recordsLinked to original sources

PubMed2004

Testing main effects and interactions in latent curve analysis.

A key strength of latent curve analysis (LCA) is the ability to model individual variability in rates of change as a function of 1 or more explanatory variables. The measurement of time plays a critical role because the explanatory variables multiplicatively interact with time in the prediction of the repeated measures. However, this interaction is not typically capitalized on in LCA because the measure of time is rather subtly incorporated via the factor loading matrix. The authors' goal is to demonstrate both analytically and empirically that classic techniques for probing interactions in multiple regression can be generalized to LCA. A worked example is presented, and the use of these techniques is recommended whenever estimating conditional LCAs in practice.

Humans↗

PubMed2003

Implications of latent trajectory models for the study of developmental psychopathology.

The field of developmental psychopathology is faced with a dual challenge. On the one hand, we must build interdisciplinary theoretical models that adequately reflect the complexity of normal and abnormal human development over time. On the other hand, to remain a viable empirical science, we must rigorously evaluate these theories using statistical methods that fully capture this complexity. The degree to which our statistical models fail to correspond to our theoretical models undermines our ability to validly test developmental theory. The broad class of random coefficient trajectory (or growth curve) models allow us to test our theories in ways not previously possible. Despite these advantages, there remain certain limits with regard to the types of questions these models can currently evaluate. We explore these issues through the pursuit of three goals. First, we provide an overview of a variety of trajectory models that can be used for rigorously testing many hypotheses in developmental psychopathology. Second, we highlight what types of research questions are well tested using these methods and what types of questions currently are not. Third, we describe areas for future statistical development and encourage the ongoing interchange between developmental theory and quantitative methodology.

Child↗

PubMed2003

Developmental course of ADHD symptomatology during the transition from childhood to adolescence: a review with recommendations.

Although historically conceptualized as a disorder that was limited to males during middle childhood, ADHD is currently conceptualized as a chronic disorder that persists into adolescence and adulthood for both sexes. Nonetheless, the veracity of adult ADHD continues to be the source of debate. In order to frame this debate, research leading to the conceptualization of ADHD as a chronic disorder is reviewed. A distinction is made between the developmental outcomes versus the developmental course of ADHD. It is concluded that although childhood ADHD is associated with negative developmental outcomes in adolescence and adulthood, questions about the developmental course of ADHD remain. Although it appears that ADHD diminishes with advancing age, a number of methodological limitations prohibit firm conclusions. Recommendations for future studies are made with an emphasis on 1) overcoming extant methodological limitations in the literature and 2) the need for theoretically derived hypotheses regarding continuity and change in ADHD symptomatology over time.

Adolescent↗