Using Bounds to Compare the Strength of Exchangeability Assumptions for Internal and External Validity.

ABSTRACT: In the absence of strong assumptions (e.g., exchangeability), only bounds for causal effects can be identified. Here we describe bounds for the risk difference for an effect of a binary exposure on a binary outcome in 4 common study settings: observational studies and randomized studies, each with and without simple random selection from the target population. Through these scenarios, we introduce randomizations for selection and treatment, and the widths of the bounds are narrowed from 2 (the width of the range of the risk difference) to 0 (point identification). We then assess the strength of the assumptions of exchangeability for internal and external validity by comparing their contributions to the widths of the bounds in the setting of an observational study without random selection f

SUBMITTER: Breskin A 

PROVIDER: S-EPMC6601532 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature