Abstract
Suppose that the longitudinal observations (Y ij , X ij , t ij ) for i = 1, . . . ,n; j = 1, . . . ,m i are modeled by the semiparamtric model \({Y_{ij}=X_{ij}^{T}\beta_{0}+g(t_{ij})+e_{ij},}\) where β 0 is a k × 1 vector of unknown parameters, g(·) is an unknown estimated function and e ij are unobserved disturbances. This article consider M-type regressions which include mean, median and quantile regressions. The M-estimator of the slope parameter β 0 is obtained through piecewise local polynomial approximation of the nonparametric component. The local M-estimator of g(·) is also obtained by replacing β 0 in model with its M-estimator and using local linear approximation. The asymptotic distribution of the estimator of β 0 is derived. The asymptotic distributions of the local M-estimators of g(·) at both interior and boundary points are also established. Various applications of our main results are given.
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The research is supported in part by National Natural Science Foundation of China (Grant No. 10671089).
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Qingguo, T. Asymptotic normality of M-estimators in a semiparametric model with longitudinal data. Metrika 69, 55–67 (2009). https://doi.org/10.1007/s00184-008-0175-6
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DOI: https://doi.org/10.1007/s00184-008-0175-6