Kaidi Kang dissertation defense – March 10
PhD candidate Kaidi Kang will present his dissertation on Monday, March 10, at 1 p.m. Central Time. His advisor is Simon Vandekar. All are invited and encouraged to attend.
The defense will be conducted in Suite 1020, Room 10105 (10th floor conference room) at 2525 West End Avenue. It will also be streamed on Zoom; for virtual access, contact the department at biostatistics[at]vumc[dot]org.
A unified effect size index and its application to improve replicability in brain-behavior association studies
Several recent studies raised concerns about the low replicability of brain-behavior association studies and showed that thousands of study participants are required for good replicability. However, massive sample sizes are often infeasible in practice. In this work, we perform analyses and meta-analyses using 63 longitudinal and cross-sectional magnetic resonance imaging (MRI) studies from the Lifespan Brain Chart Consortium (77,695 total scans) to demonstrate that optimizing study design is critical for increasing standardized effect sizes (ESs) and replicability in brain-behavior association studies. Using data from the United Kingdom Biobank (UKB) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI), we show that modifying study design through sampling schemes improves replicability. To ensure our results are generalizable, we further evaluate longitudinal sampling schemes on cognitive, psychopathology, and demographic associations with structural and functional brain outcome measures in the Adolescent Brain and Cognitive Development (ABCD) dataset. We demonstrate that commonly used longitudinal models, which assume equal between- and within-subject changes can, counterintuitively, reduce standardized ESs and replicability. Explicitly modeling the between- and within-subject effects avoids conflating them and enables optimizing the standardized ESs for each separately. Together, these results provide guidance for study designs that improve the replicability of brain-behavior association studies.
