Generalized Linear Models
Statistics for biology and health · 2005
Abstract
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The moderator-mediator variable distinction in social psychological research: Conceptual, strategic, and statistical considerations.
In this article, we attempt to distinguish between the properties of moderator and mediator variables at a number of levels. First, we seek to make theorists and researchers aware of the importance of not using the terms moderator and mediator interchangeably by carefully elaborating, both conceptually and strategically, the many ways in which moderators and mediators differ. We then go beyond this largely pedagogical function and delineate the conceptual and strategic implications of making use of such distinctions with regard to a wide range of phenomena, including control and stress, attitudes, and personality traits. We also provide a specific compendium of analytic procedures appropriate for making the most effective use of the moderator and mediator distinction, both separately and in terms of a broader causal system that includes both moderators and mediators.
A Brief Measure for Assessing Generalized Anxiety Disorder
BACKGROUND: Generalized anxiety disorder (GAD) is one of the most common mental disorders; however, there is no brief clinical measure for assessing GAD. The objective of this study was to develop a brief self-report scale to identify probable cases of GAD and evaluate its reliability and validity. METHODS: A criterion-standard study was performed in 15 primary care clinics in the United States from November 2004 through June 2005. Of a total of 2740 adult patients completing a study questionnaire, 965 patients had a telephone interview with a mental health professional within 1 week. For criterion and construct validity, GAD self-report scale diagnoses were compared with independent diagnoses made by mental health professionals; functional status measures; disability days; and health care use. RESULTS: A 7-item anxiety scale (GAD-7) had good reliability, as well as criterion, construct, factorial, and procedural validity. A cut point was identified that optimized sensitivity (89%) and specificity (82%). Increasing scores on the scale were strongly associated with multiple domains of functional impairment (all 6 Medical Outcomes Study Short-Form General Health Survey scales and disability days). Although GAD and depression symptoms frequently co-occurred, factor analysis confirmed them as distinct dimensions. Moreover, GAD and depression symptoms had differing but independent effects on functional impairment and disability. There was good agreement between self-report and interviewer-administered versions of the scale. CONCLUSION: The GAD-7 is a valid and efficient tool for screening for GAD and assessing its severity in clinical practice and research.
Stages and processes of self-change of smoking: Toward an integrative model of change.
An integrative model of change was applied to the study of 872 Ss (mean age 40 yrs) who were changing their smoking habits on their own. Ss represented the following 5 stages of change: precontemplation, contemplation, action, maintenance, and relapse. 10 processes of change were expected to receive differential emphases during particular stages of change. Results indicate that Ss (a) used the fewest processes of change during precontemplation; (b) emphasized consciousness raising during the contemplation stage; (c) emphasized self-reevaluation in both contemplation and action stages; (d) emphasized self-liberation, a helping relationship, and reinforcement management during the action stage; and (e) used counterconditioning and stimulus control the most in both action and maintenance stages. Relapsers responded as a combination of contemplaters and people in action would. Results are discussed in terms of developing a model of self-change of smoking and enhancing a more integrative general model of change. (14 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1983 American Psychological Association.