非参数回归函数的基于截尾数据的估计

NONPARAMETRIC REGRESSION FUNCTION ESTIMATION BASED ON CENSORED DATA

  • 摘要: 本文考虑截尾数据情况下非参数回归函数mx)=EY|x)的估计。具体地讲,我们面对的是这样的数学模型:T是与(X,Y)独立的随机变量,我们观测到的不是Y本身,而是Z=min(Y,T)及δ=YT。今有训练样本(Xi,Zi,δii-1及当前样本(X,z,δ),记\xi_i(\cdot)=\leftz_i \geqslant \cdot\right, \quad N^+(\cdot)=\sum_i=1^n \xi_i(\cdot), V_n(\cdot)=\prod_i=1^n\left\\frac1+N^+\left(z_i\right)2+N^+\left(z_i\right)\right\^\left\delta_i=0 z_i<0\right, \quad U_n(\cdot)=\sum_i=1^n W_n i(x) \xi_i(\cdot), 令m_n(x)=\int_0^n_n U_n(y) \mid V_n(y) d y, 其中un=F2-1(n-a),0<α<1/2为一实常数,F2(·)=PY≥·)为Y的(右侧)分布函数。在权函数Wnixi=1n及(X,Y,T)的分布函数满足一组条件下,我们证明了mnx)为mx)的强相合估计,即:mnx)→mx),a.s.(n→+∞).

     

    Abstract: Let (X1, Y1), …, (Xn, Yn) be i.i.d. Rd×R1 random vectoos, E|Y|<+∞. then mx)=EY|x) is called a regression function, Now, T1, …, Tn be i.i.d. samples of random variable T, independent of (Xi, Yii=1n. Set Fx,y)=PXx,Yy), Gt)=PTt), both F and G are unknown continuous survival functions. Based on obserations Zi=min(Xi, Yi) and δi=XiYi only, we proposed an estimate mnx) of mx). Under some conditions it is shown that mnx)→mx), a. s. (n→+∞).

     

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