Browsing by Author "Valeri, Linda"

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    Teacher Talk and Literacy Gains in Chilean Elementary Students: Teacher Participation, Lexical Diversity, and Instructional Non-present Talk
    (Elsevier Ltd, 2023) Meneses, Alejandra; Uccelli, Paola; Valeri, Linda
    © 2022Although the relation between child-caregiver non-present talk and children's language and literacy development has been extensively studied, scarce research has examined the contributions of teacher talk's conceptual, interactive, and linguistic dimensions to early literacy. Using fine-grained linguistic analysis, lessons from 16 Chilean classrooms from Pre-K to 2nd grade were coded for: conceptual (non-instructional, instructional present, instructional non-present), interactive (teacher-student talk ratio), linguistic (syntactic complexity, lexical diversity). Students were administered baseline and end-of-year literacy assessments (n=343). Controlling for school, classroom, and individual-level factors, HLM analyses revealed a positive quadratic effect of teachers’ lexical diversity on early literacy gains and a negative effect of teacher-student talk ratio, such that classrooms with greater teacher participation in instructional non-present talk tended to display lower literacy gains. A significant interaction revealed that at greater levels of teacher participation, teachers’ higher lexical diversity negatively impacted literacy gains.
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    The role of body mass index at diagnosis of colorectal cancer on Black-White disparities in survival: a density regression mediation approach
    (2022) Devick, Katrina L.; Valeri, Linda; Chen, Jarvis; Jara Vallejos, Alejandro Antonio; Bind, Marie-Abele; Coull, Brent A.
    The study of racial/ethnic inequalities in health is important to reduce the uneven burden of disease. In the case of colorectal cancer (CRC), disparities in survival among non-Hispanic Whites and Blacks are well documented, and mechanisms leading to these disparities need to be studied formally. It has also been established that body mass index (BMI) is a risk factor for developing CRC, and recent literature shows BMI at diagnosis of CRC is associated with survival. Since BMI varies by racial/ethnic group, a question that arises is whether differences in BMI are partially responsible for observed racial/ethnic disparities in survival for CRC patients. This article presents new methodology to quantify the impact of the hypothetical intervention that matches the BMI distribution in the Black population to a potentially complex distributional form observed in the White population on racial/ethnic disparities in survival. Our density mediation approach can be utilized to estimate natural direct and indirect effects in the general causal mediation setting under stronger assumptions. We perform a simulation study that shows our proposed Bayesian density regression approach performs as well as or better than current methodology allowing for a shift in the mean of the distribution only, and that standard practice of categorizing BMI leads to large biases when BMI is a mediator variable. When applied to motivating data from the Cancer Care Outcomes Research and Surveillance (CanCORS) Consortium, our approach suggests the proposed intervention is potentially beneficial for elderly and low-income Black patients, yet harmful for young or high-income Black populations.
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    The Role of Body Mass Index at Diagnosis on Black-White Disparities in Colorectal Cancer Survival: A Density Regression Mediation Approach
    (2018) Devick, Katrina L.; Valeri, Linda; Chen, Jarvis; Jara, Alejandro; Bind, Marie-Abèle; Coull, Brent A.
    The study of racial/ethnic inequalities in health is important to reduce the uneven burden of disease. In the case of colorectal cancer (CRC), disparities in survival among non-Hispanic Whites and Blacks are well documented, and mechanisms leading to these disparities need to be studied formally. It has also been established that body mass index (BMI) is a risk factor for developing CRC, and recent literature shows BMI at diagnosis of CRC is associated with survival. Since BMI varies by racial/ethnic group, a question that arises is whether disparities in BMI is partially responsible for observed racial/ethnic disparities in CRC survival. This paper presents new methodology to quantify the impact of the hypothetical intervention that matches the BMI distribution in the Black population to a potentially complex distributional form observed in the White population on racial/ethnic disparities in survival. We perform a simulation that shows our proposed Bayesian density regression approach performs as well as or better than current methodology allowing for a shift in the mean of the distribution only, and that standard practice of categorizing BMI leads to large biases. When applied to motivating data from the Cancer Care Outcomes Research and Surveillance (CanCORS) Consortium, our approach suggests the proposed intervention is potentially beneficial for elderly and low income Black patients, yet harmful for young and high income Black populations.