Talks

All talks licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Creative Commons Attribution-ShareAlike 4.0 International License

Nonparametric generalized raking

December 17, 2024

Talk, IMS International Conference on Statistics and Data Science (ICSDS), Nice, France

I discuss an extension of generalized raking to estimate marginal parameters (e.g., the average treatment effect) and obtain valid inference using machine learning.

Slides

Design considerations for subgroup analyses in cluster-randomized trials based on aggregated individual-level predictors

August 06, 2024

Talk, JSM 2024, Portland, Oregon

In research assessing the effect of an intervention or exposure, a key secondary objective often involves assessing differential effects of this intervention or exposure in subgroups of interest; this is often referred to as assessing effect modification or heterogeneity of treatment effects (HTE). Observed HTE can have important implications for policy, including intervention strategies (e.g., will some patients benefit more from intervention than others?) and prioritizing resources (e.g., to reduce observed health disparities). Analysis of HTE is well understood in studies where the independent unit is an individual. In contrast, in studies where the independent unit is a cluster (e.g., a hospital or school) and a cluster-level outcome is used in the analysis, it is less well understood how to proceed if the HTE analysis of interest involves an individual-level characteristic (e.g., self-reported race) that must be aggregated at the cluster level. Through simulations, we show that only individual-level models have power to detect HTE by individual-level variables; if outcomes must be defined at the cluster level, then there is often low power to detect HTE by the corresponding aggregated variables. We illustrate the challenges inherent to this type of analysis in a study assessing the effect of an intervention on increasing COVID-19 booster vaccination rates at long-term care centers.

I also gave an invited poster presentation on based this talk at the JSM opening mixer on August 4.

Slides

Design considerations for subgroup analyses in cluster-randomized trials based on aggregated individual-level predictors

June 12, 2024

Talk, WNAR 2024, Fort Collins, Colorado

In research assessing the effect of an intervention or exposure, a key secondary objective often involves assessing differential effects of this intervention or exposure in subgroups of interest; this is often referred to as assessing effect modification or heterogeneity of treatment effects (HTE). Observed HTE can have important implications for policy, including intervention strategies (e.g., will some patients benefit more from intervention than others?) and prioritizing resources (e.g., to reduce observed health disparities). Analysis of HTE is well understood in studies where the independent unit is an individual. In contrast, in studies where the independent unit is a cluster (e.g., a hospital or school) and a cluster-level outcome is used in the analysis, it is less well understood how to proceed if the HTE analysis of interest involves an individual-level characteristic (e.g., self-reported race) that must be aggregated at the cluster level. Through simulations, we show that only individual-level models have power to detect HTE by individual-level variables; if outcomes must be defined at the cluster level, then there is often low power to detect HTE by the corresponding aggregated variables. We illustrate the challenges inherent to this type of analysis in a study assessing the effect of an intervention on increasing COVID-19 booster vaccination rates at long-term care centers.

Slides

Statistics in Infectious Disease Research

March 27, 2024

Talk, University of Washington Biostatistics 111, Seattle, Washington

Lecture on some of the ways that statistics is used in infectious disease research to students in UW Biostatistics 111.

Slides

Inference for Model-Agnostic Variable Importance

January 25, 2024

Talk, Institut Curie Statistics Seminar, Paris, France

In many applications, it is of interest to assess the relative contribution of features (or subsets of features) toward the goal of predicting a response – in other words, to gauge the variable importance of features. In this talk, I will discuss a model-agnostic notion of variable importance and general conditions under which valid inference on the true importance can be obtained, even when machine learning-based techniques are used as part of estimation. We define variable importance as a population-level contrast between the oracle predictiveness of all available features versus all features except those under consideration. I provide several examples of predictiveness measures, including for right-censored outcomes, and illustrate the use of the proposed methods with data from a study of an antibody against HIV-1 infection.

Slides

Statistics in Infectious Disease Research

April 05, 2023

Talk, University of Washington Biostatistics 111, Seattle, Washington

Lecture on some of the ways that statistics is used in infectious disease research to students in UW Biostatistics 111.

Slides

Inference for Model-Agnostic Longitudinal Variable Importance

December 17, 2022

Talk, 15th International Conference of the European Consortium for Informatics and Mathematics Working Group on Computational and Methodological Statistics (CMStatistics), London, United Kingdom

I discuss a framework for inference on general model-agnostic variable importance measures and possible summary measures for longitudinal variable importance.

Slides

Inference for Model-Agnostic Variable Importance

June 19, 2022

Talk, International Chinese Statistical Association Applied Statistics Symposium, Gainesville, Florida

I discuss a framework for inference on general model-agnostic variable importance measures and possible summary measures for longitudinal variable importance.

Model-Agnostic Variable Importance and Selection

April 28, 2022

Talk, University of Washington Department of Biostatistics Seminar Series, Virtual

I discuss a framework for inference on general model-agnostic variable importance measures, and how this framework can be used to perform variable selection. I also briefly discuss several directions of current work, including longitudinal variable importance; a measure of how important variables are for tailoring treatment; and fairness-aware variable importance.

Inference for Model-Agnostic Variable Importance

February 24, 2022

Talk, American Statistical Association Statistical Learning and Data Science Webinar Series, Virtual

I discuss a framework for inference on general model-agnostic variable importance measures.

Statistics in Infectious Disease Research

December 02, 2020

Talk, Roanoke Valley Governor's School Computational Biology Course, Virtual

Guest lecture on some of the ways that statistics is used in infectious disease research in the Computational Biology course at Roanoke Valley Governor’s School.