# The Research Group of Mark van der Laan

## Estimating effects based upon community-level interventions and optimal interventions

This post is part of our Q&A series. A question from graduate students in our Fall 2020 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, We have been discussing questions regarding community-based interventions and we would like to hear your input on the following three questions: When we estimate the causal effects of community-based interventions, we can use baseline variables to block the effect of the environment on the outcome, so that we can change the problem into individual levels.

## Using a data-adaptive target parameter and CV-TMLE in survival analysis

This post is part of our Q&A series. A question from graduate students in our Fall 2020 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, Within the field of industrial hygiene and occupational epidemiology there is interest in linking possible occupational exposures to deleterious health outcomes, most usually various cancers. Obviously in such a setting, it is nearly impossible without individual chemical biomarkers to have causal identifiability for a specific exposure (for example lead, pesticides, benzene, etc.

## Using time-varying covariates in evaluating the causal effect of a single time point intervention

This post is part of our Q&A series. A question from graduate students in our Fall 2020 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, We have an observational study with fixed baseline intervention, $A$ for statin use vs. no statin use, along with baseline covariates, $L$ such as age, gender, marital status, hypertension, diabetes, hypercholesterolemia, coronary artery disease. Our goal is to predict conversion to the more impaired stage of Alzheimer’s disease.

## TMLE for multi-level treatments and methods for sensitivity analysis

This post is part of our Q&A series. A question from graduate students in our Fall 2020 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, We had two questions for you, 1. How to apply TMLE to treatment with multiple levels and conduct inference? For example, if the potential outcomes are $Y_i(0), Y_i(1), \ldots, Y_i(K)$ for $K$ different possible treatments, i.e., possible values for $A_i$ are from $1$ to $K$, how would TMLE work?

## Estimating causal effects with instrumental variables in survival analysis

This post is part of our Q&A series. A question from graduate students in our Fall 2020 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, In survival analysis, what methods should we use to estimate counterfactuals and causal effect if the conditional independence assumption is violated? For instance, the instrumental variable method in econometrics and Mendelian randomization in biostatistics deal with the unmeasured confounding problem.

## Two-stage sampling and survival analysis

This post is part of our Q&A series. A question from graduate students in our Fall 2019 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, We are wondering under your framework, how to deal with a situation when only right-censored data has a full set of covariates, while the covariates for the non-right-censored data are largely missing. To be specific, we want to find the relation between peoples’ matching property and their marriage durations.

## Estimating the sample average treatment effect under effect modification in a cluster randomized trial

This post is part of our Q&A series. A question from graduate students in our Fall 2019 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, We were wondering about the application of TMLE and superlearner to cluster-randomized study designs, and the adoption of the sample average treatment effect (SATE) as an efficient estimator. From our understanding, although the SATE is not formally identifiable in a finite setting, it is nevertheless an efficient estimate due to its asymptotic behavior (TMLE for the population effect is asymptotically linear and has an asymptotically conservative variance estimator).

## Longitudinal causal model under obscured time-ordering

This post is part of our Q&A series. A question from graduate students in our Fall 2019 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, Suppose we have a longitudinal data structure where information about the intervention and time-varying covariate is collected simultaneously, and their temporal ordering is obscured. For instance, data is collected at monthly health checkups, where $A(t)$ is the subject’s healthy eating habits in the past month, and $L(t)$ is the occurrence of heartburn in the past month.

## Positivity assumption violations and TMLE for longitudinal data with many time-varying covariates

This post is part of our Q&A series. A question from graduate students in our Fall 2019 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, For longitudinal data such as $O=(L_0,A_0,Y_0,L_1,A_1,Y_1,L_2,A_2,Y_2,\ldots )$, we can use G-computation formula with sequential regression method if we treat time $t$ as discrete variable. And you also mentioned that there are more general methods which can deal with the case when $t$ is continuous.

## Simultaneous inference with the Kaplan-Meier estimator of survival

This post is part of our Q&A series. A question from graduate students in our Fall 2019 offering of “Biostatistical Methods: Survival Analysis and Causality” at UC Berkeley: Question: Hi Mark, First of all, I have doubts regarding the simultaneous confidence interval for Kaplan- Meier, since I am not necessarily interested in inference for a parameter. I would like > to know if the 95% confidence band for my KM estimator will hold using the same formula > we did in our R lab without covariates (taken from lectures).