title: Causal inference and the data-fusion problem.
abstract: We review concepts, principles, and tools that unify current approaches to causal analysis and attend to new challenges presented by big data. In particular, we address the problem of data fusion-piecing together multiple datasets collected under heterogeneous conditions (i.e., different populations, regimes, and sampling methods) to obtain valid answers to queries of interest. The availability of multiple heterogeneous datasets presents new opportunities to big data analysts, because the knowledge that can be acquired from combined data would not be possible from any individual source alone. However, the biases that emerge in heterogeneous environments require new analytical tools. Some of these biases, including confounding, sampling selection, and cross-population biases, have been addressed in isolation, largely in restricted parametric models. We here present a general, nonparametric framework for handling these biases and, ultimately, a theoretical solution to the problem of data fusion in causal inference tasks.
authors.affiliation: Department of Computer Science, University of California, Los Angeles, CA 90095; Department of Computer Science, Purdue University, West Lafayette, IN 47907 eb@purdue.edu.
authors.forename: Elias
authors.initials: E
authors.lastname: Bareinboim
authors.affiliation: Department of Computer Science, University of California, Los Angeles, CA 90095;
authors.forename: Judea
authors.initials: J
authors.lastname: Pearl
keywords: causal inference; counterfactuals; external validity; selection bias; transportability