Instrumental-Variables Simultaneous Equations Model of Physical Activity and Body Mass Index: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Authors
Meyer, Katie A.Guilkey, David K.
Tien, Hsiao-Chuen
Kiefe, Catarina I.
Popkin, Barry M.
Gordon-Larsen, Penny
UMass Chan Affiliations
Department of Quantitative Health SciencesDocument Type
Journal ArticlePublication Date
2016-09-15Keywords
UMCCTS fundingbody mass index
endogeneity
epidemiologic methods
fixed effects
health behaviors
instrumental variables
semiparametric methods
simultaneous equations
Behavior and Behavior Mechanisms
Epidemiology
Public Health
Metadata
Show full item recordAbstract
We used full-system-estimation instrumental-variables simultaneous equations modeling (IV-SEM) to examine physical activity relative to body mass index (BMI; weight (kg)/height (m)(2)) using 25 years of data (1985/1986 to 2010/2011) from the Coronary Artery Risk Development in Young Adults (CARDIA) Study (n = 5,115; ages 18-30 years at enrollment). Neighborhood environment and sociodemographic instruments were used to characterize physical activity, fast-food consumption, smoking, alcohol consumption, marriage, and childbearing (women) and to predict BMI using semiparametric full-information maximum likelihood estimation to control for unobserved time-invariant and time-varying residual confounding and differential measurement error through model-derived discrete random effects. Comparing robust-variance ordinary least squares, random-effects regression, fixed-effects regression, single-equation-estimation IV-SEM, and full-system-estimation IV-SEM, estimates from random- and fixed-effects models and the full-system-estimation IV-SEM were unexpectedly similar, despite the lack of control for residual confounding with the random-effects estimator. Ordinary least squares tended to overstate the significance of health behaviors in BMI, while results from single-equation-estimation IV-SEM were notably different, revealing the impact of weak instruments in standard instrumental-variable methods. Our robust findings for fixed effects (which does not require instruments but has a high cost in lost degrees of freedom) and full-system-estimation IV-SEM (vs. standard IV-SEM) demonstrate potential for a full-system-estimation IV-SEM method even with weak instruments.Source
Am J Epidemiol. 2016 Sep 15;184(6):465-76. doi: 10.1093/aje/kww010. Epub 2016 Sep 9. Link to article on publisher's siteDOI
10.1093/aje/kww010Permanent Link to this Item
http://hdl.handle.net/20.500.14038/29045PubMed ID
27614300Related Resources
Link to Article in PubMedae974a485f413a2113503eed53cd6c53
10.1093/aje/kww010