nayana-c1.867c992ae9100904cc61c84591adf0f8f863e0387e30f0d0dbc86640e9f50a1a.en.train.313231

The task

Which of the following is NOT mentioned as a reference in the text? A. P. R. Rosenbaum and D. B. Rubin, The central role of the propensity score in observational studies for causal effects, Biometrika, 70 (1983), pp. 41-55. B. D. B. Rubin, Multivariate Matching Methods That Are Equal Percent Bias Reducing, I: Some Examples, Biometrics, 32 (1976), pp. 109-120. C. J. S. Sekhon, Multivariate and Propensity Score Matching Software with Automated Balance Optimization: The Matching package for R. unpublished, 2007. D. Y. Tille and A. Matei, sampling: Functions for drawing and calibrating samples, 21st January 2011. R package version 2.4. Return only the single uppercase letter of the correct option.