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Robust learning for optimal treatment decision with NP-dimensionality. (English) Zbl 1419.62445

Summary: In order to identify important variables that are involved in making optimal treatment decision, the last author, H. Zhang and D. Zeng [“Variable selection for optimal treatment decision”, Stat. Methods Med. Res. 22, No. 5, 493–504 (2013; doi:10.1177/0962280211428383] proposed a penalized least squared regression framework for a fixed number of predictors, which is robust against the misspecification of the conditional mean model. Two problems arise: (i) in a world of explosively big data, effective methods are needed to handle ultra-high dimensional data set, for example, with the dimension of predictors is of the non-polynomial (NP) order of the sample size; (ii) both the propensity score and conditional mean models need to be estimated from data under NP dimensionality. In this paper, we propose a robust procedure for estimating the optimal treatment regime under NP dimensionality.
In both steps, penalized regressions are employed with the non-concave penalty function, where the conditional mean model of the response given predictors may be misspecified. The asymptotic properties, such as weak oracle properties, selection consistency and oracle distributions, of the proposed estimators are investigated. In addition, we study the limiting distribution of the estimated value function for the obtained optimal treatment regime. The empirical performance of the proposed estimation method is evaluated by simulations and an application to a depression dataset from the STAR study.

MSC:

62P10 Applications of statistics to biology and medical sciences; meta analysis
62J07 Ridge regression; shrinkage estimators (Lasso)
62G35 Nonparametric robustness
62F12 Asymptotic properties of parametric estimators
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