A two-stage Generalized Method of Moments model for feedback with time-dependent covariates

2020 ◽  
pp. 096228022098140
Author(s):  
Elsa Vazquez-Arreola

Correlated observations in longitudinal studies are often due to repeated measures on the subjects. Additionally, correlation may be realized due to the association between responses at a particular time and the predictors at earlier times. There are also feedback effects (relation between responses in the present and the covariates at a later time), though these are not always relevant and are often ignored. All these cases of correlation must be accounted for as they can have different effects on the regression coefficients. Several authors have provided models that reflect the direct and delayed impact of covariates on the response, utilizing valid moment conditions to estimate the relevant regression coefficients. However, there are applications when one cannot ignore the effect of the responses on future covariates. A two-stage model to account for the feedback, modeling the direct as well as the delayed effects of the covariates on future responses and vice versa is presented. The use of the two-stage model is demonstrated by revisiting child morbidity and its impact on future values of body mass index using Philippines health data. Also, obesity status and its feedback effects on physical activity and depression levels using the Add Health dataset are analyzed.

2020 ◽  
Vol 33 (5) ◽  
pp. e100263
Author(s):  
Elsa Vazquez Arreola ◽  
Jeffrey R Wilson ◽  
Ding-Geng Chen

In studies on psychiatry and neurodegenerative diseases, it is common to have data that are correlated due to the hierarchical structure in data collection or to repeated measures on the subject longitudinally. However, the feedback effect created due to time-dependent covariates in these studies is often overlooked and seldom modelled. This article reviews the methodological development of feedback effects with marginal models for longitudinal data and discusses their implementation.


1997 ◽  
Author(s):  
Saul Sternberg ◽  
Teresa Pantzer
Keyword(s):  

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yaroslava E. Poroshyna ◽  
Aleksander I. Lopato ◽  
Pavel S. Utkin

Abstract The paper contributes to the clarification of the mechanism of one-dimensional pulsating detonation wave propagation for the transition regime with two-scale pulsations. For this purpose, a novel numerical algorithm has been developed for the numerical investigation of the gaseous pulsating detonation wave using the two-stage model of kinetics of chemical reactions in the shock-attached frame. The influence of grid resolution, approximation order and the type of rear boundary conditions on the solution has been studied for four main regimes of detonation wave propagation for this model. Comparison of dynamics of pulsations with results of other authors has been carried out.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Dalton J. Hance ◽  
Katie M. Moriarty ◽  
Bruce A. Hollen ◽  
Russell W. Perry

An amendment to this paper has been published and can be accessed via the original article.


2019 ◽  
Vol 675 ◽  
pp. 658-666 ◽  
Author(s):  
Wei Wang ◽  
Feiyue Mao ◽  
Bin Zou ◽  
Jianping Guo ◽  
Lixin Wu ◽  
...  

2011 ◽  
Vol 20 (6) ◽  
pp. 407-408 ◽  
Author(s):  
Azim F. Shariff ◽  
Jessica L. Tracy

We appreciate Barrett’s (2011, this issue) comments and her discussion of how our two-stage model is and is not consistent with Darwin’s views on the evolution of emotion expressions. Like many pioneering books, Darwin’s The Expression of Emotions in Man and Animals represents a flurry of novel and revolutionary, yet often inconsistent, ideas, which lend themselves to different readings. However, while the historical perspective Barrett provides is useful, the scientific conversation on emotion expressions has evolved since Darwin. Here, we briefly discuss why the two alternative explanations Barrett offers for the origins of emotion expressions—expressions as cultural symbols and/or as evolutionary byproducts—are both untenable in light of existing research. We also note that although evidence for our two-stage model is currently incomplete, our goal was not to tell a complete story. Instead, we sought to offer the best emerging explanation for the existing research and provide a path for future empirical work that can test it.


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