Abstract
With technological advances, collection of intensive longitudinal data (ILD), such as ecological momentary assessments, becomes
more widespread in prevention science. In ILD studies, researchers are often interested in the effects of time-varying covariates
(TVCs) on a time-varying outcome to discover correlates and triggers of target behaviors (e.g., how momentary changes in affect
relate to momentary smoking urges). Traditional analytical methods, however, impose important constraints, assuming a constant
effect of the TVC on the outcome. In the current paper, we describe a time-varying effect model (TVEM) and its applications
to data collected as part of a smoking-cessation study. Differentiating between groups of short-term successful quitters (N = 207) and relapsers (N = 40), we examine the effects of momentary negative affect and abstinence self-efficacy on the intensity of smoking urges
in each subgroup in the 2 weeks following a quit attempt. Successful quitters demonstrated a rapid reduction in smoking urges
over time, a gradual decoupling of the association between negative affect and smoking urges, and a consistently strong negative
effect of self-efficacy on smoking urges. In comparison, relapsers exhibited a high level of smoking urges throughout the
post-quit period, a time-varying and, generally, weak effect of self-efficacy on smoking urges, and a gradual reduction in
the strength of the association between negative affect and smoking urges. Implications of these findings are discussed. The
TVEM is made available to applied prevention researchers through a SAS macro.
more widespread in prevention science. In ILD studies, researchers are often interested in the effects of time-varying covariates
(TVCs) on a time-varying outcome to discover correlates and triggers of target behaviors (e.g., how momentary changes in affect
relate to momentary smoking urges). Traditional analytical methods, however, impose important constraints, assuming a constant
effect of the TVC on the outcome. In the current paper, we describe a time-varying effect model (TVEM) and its applications
to data collected as part of a smoking-cessation study. Differentiating between groups of short-term successful quitters (N = 207) and relapsers (N = 40), we examine the effects of momentary negative affect and abstinence self-efficacy on the intensity of smoking urges
in each subgroup in the 2 weeks following a quit attempt. Successful quitters demonstrated a rapid reduction in smoking urges
over time, a gradual decoupling of the association between negative affect and smoking urges, and a consistently strong negative
effect of self-efficacy on smoking urges. In comparison, relapsers exhibited a high level of smoking urges throughout the
post-quit period, a time-varying and, generally, weak effect of self-efficacy on smoking urges, and a gradual reduction in
the strength of the association between negative affect and smoking urges. Implications of these findings are discussed. The
TVEM is made available to applied prevention researchers through a SAS macro.
- Content Type Journal Article
- Pages 1-12
- DOI 10.1007/s11121-011-0264-z
- Authors
- Mariya P. Shiyko, Department of Counseling & Applied Educational Psychology, Bouve College of Health Sciences, Northeastern University, 404 INV, 360 Huntington Ave, Boston, MA 02115, USA
- Stephanie T. Lanza, The Methodology Center, 204 E. Calder Way, Suite 400, State College, PA 16801, USA
- Xianming Tan, The Methodology Center, 204 E. Calder Way, Suite 400, State College, PA 16801, USA
- Runze Li, Department of Statistics and The Methodology Center, The Pennsylvania State University, 326 Thomas Building, University Park, PA 16802, USA
- Saul Shiffman, Departments of Psychology, Psychiatry, and Pharmaceutical Sciences, University of Pittsburgh, 210 S. Bouquet Street, Pittsburgh, PA 15260, USA
- Journal Prevention Science
- Online ISSN 1573-6695
- Print ISSN 1389-4986