An estimating equations approach to fitting latent exposure models with longitudinal health outcomes

The analysis of data arising from environmental health studies which collect a large number of measures of exposure can benefit from using latent variable models to summarize exposure information. However, difficulties with estimation of model parameters may arise since existing fitting procedures for linear latent variable models require correctly specified residual variance structures for unbiased estimation of regression parameters quantifying the association between (latent) exposure and health outcomes. We propose an estimating equations approach for latent exposure models with longitudinal health outcomes which is robust to misspecification of the outcome variance. We show that compared to maximum likelihood, the loss of efficiency of the proposed method is relatively small when the model is correctly specified. The proposed equations formalize the ad-hoc regression on factor scores procedure, and generalize regression calibration. We propose two weighting schemes for the equations, and compare their efficiency. We apply this method to a study of the effects of in-utero lead exposure on child development.Comment: Published in at http://dx.doi.org/10.1214/08-AOAS226 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Estimators for longitudinal latent exposure models: examining measurement model assumptions

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136711/1/sim7268_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136711/2/sim7268.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136711/3/sim7268-sup-0001-Supplementary.pd

Hierarchical multiple informants models: examining food environment contributions to the childhood obesity epidemic

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102625/1/sim5967.pd

La Gestión Administrativa orientada al marketing mix de la empresa “Flowers Mers”.

The present research work entitled; administrative management oriented to the marketing mix of the company “Flowers Mers”. It was evident that the company administratively works empirically based on the experience and intuition of the owners. Furthermore, the company does not have the ability to set prices because large exporting companies have control of the market, including costs and promotions for the sale of summer flowers, which generates a monopoly situation. Thus, the lack of knowledge of the market has had a negative impact on the sales of the company “Flowers Mers”, therefore, this study aims to; Determine the context of administrative management based on the marketing mix of the “Flowers Mers” florist in the Guaytacama parish. For this, a qualitative methodology was applied that included the participation of the owner of the company. The results showed that flower shops exhibit a wide range of summer flowers with the absence of tariff levies and distribution channels while the others represent a decrease in market share. In administrative management, most of these companies apply the processes of said variable unconsciously (planning, organizing, directing and controlling). Therefore, it is concluded that the florist “Flowers Mers” works empirically; which implies that the company does not apply the marketing mix adequately.El presente trabajo de investigación titulado, la gestión administrativa orientada al marketing mix de la empresa “Flowers Mers”. Se evidenció que la empresa administrativamente trabaja de manera empírica basada en la experiencia y la intuición de los propietarios. Además, la empresa no tiene la capacidad de fijar los precios debido a que las grandes empresas exportadoras tienen el control del mercado, incluyendo los costos y promociones para la venta de flores de verano, lo que genera una situación de monopolio. Así pues, la falta de conocimiento del mercado ha tenido un impacto negativo en las ventas de la empresa “Flowers Mers”, por ende, este estudio tiene como objetivo; Determinar el contexto de la gestión administrativa en base al marketing mix de la florícola “Flowers Mers” de la parroquia Guaytacama. Para esto, se aplicó una metodología cualitativa que incluyó la participación del propietario de la empresa. Los resultados evidenciaron que las florícolas exhiben una amplia gama de flores de verano con la ausencia de gravámenes arancelarios y canales de distribución mientras que las demás representan una disminución en la participación del mercado. En la gestión administrativa, la mayoría de estas empresas aplican los procesos de dicha variable de manera inconsciente (planificación, organizar, dirigir y controlar). Por lo tanto, se concluye que la florícola “Flowers Mers”, trabaja de manera empírica; lo que implica que la empresa no aplique de una manera adecuada el marketing mix

Perinatal Lead (Pb) Exposure Results in Sex-Specific Effects on Food Intake, Fat, Weight, and Insulin Response across the Murine Life-Course

Developmental lead (Pb) exposure has been associated with lower body weight in human infants and late onset obesity in mice. We determined the association of perinatal Pb exposure in mice with changes in obesity-related phenotypes into adulthood. Mice underwent exposure via maternal drinking water supplemented with 0 (control), 2.1 (low), 16 (medium), or 32 (high) ppm Pb-acetate two weeks prior to mating through lactation. Offspring were phenotyped at ages 3, 6, and 9 months for energy expenditure, spontaneous activity, food intake, body weight, body composition, and at age 10 months for glucose tolerance. Data analyses were stratified by sex and adjusted for litter effects. Exposed females and males exhibited increased energy expenditure as compared to controls (p<0.0001 for both). In females, horizontal activity differed significantly from controls (p = 0.02) over the life-course. Overall, food intake increased in exposed females and males (p<0.0008 and p<0.0001, respectively) with significant linear trends at 9 months in females (p = 0.01) and 6 months in males (p<0.01). Body weight was significantly increased in males at the medium and high exposures (p = 0.001 and p = 0.006). Total body fat differed among exposed females and males (p<0.0001 and p<0.0001, respectively). Insulin response was significantly increased in medium exposure males (p<0.05). Perinatal Pb exposure at blood lead levels between 4.1 µg/dL and 32 µg/dL is associated with increased food intake, body weight, total body fat, energy expenditure, activity, and insulin response in mice. Physiological effects of developmental Pb exposure persist and vary according to sex and age

Sleep‐disordered breathing and poststroke outcomes

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150527/1/ana25515_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150527/2/ana25515.pd

Estimating Co-Occurring Behavioral Trajectories Within a Neighborhood Context: A Case Study of Multivariate Transition Models for Clustered Data

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63092/1/cerda_estimating co-occurring_2008.pd