Hi everyone!

This week at the Applied Statistics Workshop we will be welcoming Peng Ding, Postdoctoral Fellow in Statistics at Harvard University, and Assistant Professor of Statistics at Berkeley beginning January 2016.  He will be presenting work entitled Sensitivity Analysis Without Assumptions.  Please find the abstract below and on the website.

As usual, we will meet in CGIS Knafel Room 354 from noon to 1:30pm, and lunch will be provided.  See you all there! To view previous Applied Statistics presentations, please visit the website.

-- Aaron Kaufman

Title: Sensitivity Analysis Without Assumptions

Unmeasured confounding may undermine the validity of causal inference with observational studies. Sensitivity analysis provides an attractive way to partially circumvent this issue by assessing the potential influence of unmeasured confounding on the causal conclusions. However, previous sensitivity analysis approaches often make strong and untestable assumptions such as having a confounder that is binary, or having no interaction between the effects of the exposure and the confounder on the outcome, or having only one confounder. Without imposing any assumptions on the confounder or confounders, we derive a bounding factor and a sharp inequality such that the sensitivity analysis parameters must satisfy the inequality if an unmeasured confounder is to explain away the observed effect estimate or reduce it to a particular level. Our approach is easy to implement and involves only two sensitivity parameters. Surprisingly, our bounding factor, which makes no simplifying assumptions, is no more conservative than a number of previous sensitivity analysis techniques that do make assumptions. Our new bounding factor implies not only the traditional Cornfield conditions that both the relative risk of the exposure on the confounder and that of the confounder on the outcome must satisfy, but also a high threshold that the maximum of these relative risks must satisfy. Furthermore, this new bounding factor can be viewed as a measure of the strength of confounding between the exposure and the outcome induced by a confounder.