A Note on Recurring Misconceptions When Fitting Nonlinear Mixed Models

Nonlinear mixed-effects (NLME) models are used when analyzing continuous repeated measures data taken on each of a number of individuals where the focus is on characteristics of complex, nonlinear individual change. Challenges with fitting NLME models and interpreting analytic results have been well documented in the statistical literature. However, parameter estimates as well as fitted functions from NLME analyses in recent articles have been misinterpreted, suggesting the need for clarification of these issues before these misconceptions become fact. These misconceptions arise from the choice of popular estimation algorithms, namely, the first-order linearization method (FO) and Gaussian-Hermite quadrature (GHQ) methods, and how these choices necessarily lead to population-average (PA) or subject-specific (SS) interpretations of model parameters, respectively. These estimation approaches also affect the fitted function for the typical individual, the lack-of-fit of individuals’ predicted trajectories, and vice versa.     

Treatment Populations,Services, and Outcomes for Cocaine and Crack-Cocaine Dependence

This paper analyzes demographic and other pretreatment characteristics, measures of treatment services received, and treatment outcomes of participantsin the National Treatment Improvement Evaluation Study (NTIES), a large-scale longitudinal study of substance abuse treatment (D. R. Gerstein et al., 1997; R. A. Johnson & D. R. Gerstein, 2000). The focus here is those treated primarily for cocaine powder or crack-cocaine dependence, compared with those in treatment for other substances, particularly heroin. Crack-dependent users tend to be female and black, older than primary marijuana or alcohol users but younger than those in treatment for heroin. Primary cocaine powder or crack users are likely to have entered treatment under pressure from the criminal justice system. After treatment there are substantial reductions in use of cocaine powder and crack, especially among participants with fewer prior treatment episodes and lower pretreatment intensity of use. Longer duration and intensity of treatment result in greater reductions in cocaine and crack use.     

Unequal Power Relationships Within a Cooperative or Corn petit ive Context

Sixty undergraduates negotiated an exchange of resources in dyads. They had either high or low power relative to the other and were within a competitive or cooperative context. Results support the hypothesis that these contexts affect unequal power persons' interaction and relationship. Compared to those in the cooperative context, high and lower power participants in the competitive context suspected each other, refused to exchange resources, developed negative attitudes toward each other, and associated power with control. In addition, low power participants in the competitive context indicated considerable insecurity about the interaction. These results highlight that previous literature has tended, often implicitly, to consider power and unequal power relationships within a competitive context. The dynamics proposed by this literature that inequality of power undermines negotiations and that power refers to the control of another were found to be much stronger within a competitive context than a cooperative one. Whereas the emphasis of the literature has been on power equalization, findings suggest that placing power differences in a cooperative con text can contribute to effective working relationships.     

Taking the U.S. Patent Office Criteria Seriously: A Quantitative Three-Criterion Creativity Definition and Its Implications

Although creativity has recently attracted considerable theoretical and empirical research, researchers have yet to reach a consensus on how best to define the phenomenon. To help establish a consensus, a definition is proposed that is based on the three criteria used by the United States Patent Office to evaluate applications for patent protection. The modified version uses the criteria of novelty, utility, and surprise. Moreover, creativity assessments based on these three criteria are quantitative and multiplicative rather than qualitative or additive. This three-criterion definition then leads to four implications regarding (a) the limitations to domain-specific expertise, (b) the varieties of comparable creativities, (c) the contrast between subjective and objective evaluations, and (d) the place of blind variation and selective retention in the creative process. These implications prove that adding the third criterion has critical consequences for understanding the phenomenon. Creativity is not only treated with superior sophistication, but also paradoxes that appear using the most common two-criterion definition readily disappear when the third criterion is included in the analysis. Hence, the conceptual differences between two- and three-criterion definitions are not trivial.     

Relationship Satisfaction: Impact and Consequences for Women's Emotional Health and Treatment

This study uses feminist theory to examine the variables of relationship length and relationship satisfaction as predicators of both self-esteem and emotional functioning for women. Using a national sample of data gathered from 1,257 female survey respondents this study found significant relationships between emotional functioning, self-esteem, and self-reported relationship satisfaction which was supported by regression testing and path analysis. In addition, a significant negative relationship was noted between a woman's self-esteem and her with-holding of verbalized displeasure or disagreement with her partner. Implications for women in therapy were discussed.