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Limit theorems for the ratio of the Kaplan-Meier estimator or the Altshuler estimator to the true survival function
Authors:Zheng Zukang
Institution:(1) Department of Statistics and Operations Research, Fudan University, 200433 Shanghai, China
Abstract:LetX 1,X 2, ...,X n be a sequence of nonnegative independent random variables with a common continuous distribution functionF. LetY 1,Y 2, ...,Y n be another sequence of nonnegative independent random variables with a common continuous distribution functionG, also independent of {X i }. We can only observeZ i =min(X i ,Y i ), and 
$$\delta _i  = I_{(X_i  \leqslant Y_i )} $$
. LetH=1−(1−F)(1−G) be the distribution function ofZ. In this paper, the limit theorems for the ratio of the Kaplan-Meier estimator 
$$\hat S_n (t)$$
or the Altshuler estimator 
$$\tilde S_n (t)$$
to the true survival functionS(t) are given. It is shown that (1)P(n)=1 i.o.)=0 ifF H ) < 1 andP n =0 i.o. )=0 ifGH) > 1 where δ(n) is the corresponding indicator function of 
$$T = Z_{(n)}  = \mathop {\max }\limits_{1 \leqslant i \leqslant n} Z_i ,\tau _H  = \inf \{ t:H(t) = 1\} ;(2)\mathop {\sup }\limits_{t \leqslant T_n } \left| {\frac{{\hat S_n (t)}}{{S(t)}} - 1} \right|,\mathop {\sup }\limits_{t \leqslant T_n } \left| {\frac{{S(t)}}{{\hat S_n (t)}} - 1} \right|,\mathop {\sup }\limits_{t \leqslant T_n } \left| {\frac{{\tilde S_n (t)}}{{S(t)}} - 1} \right|$$
and 
$$\mathop {\sup }\limits_{t \leqslant T_n } \left| {\frac{{S(t)}}{{\hat S_n (t)}} - 1} \right|$$
have the same order 
$$O\left( {n^{\frac{{ - 1 + \alpha }}{2}} (\log n)^{\frac{{1 - \beta }}{2}} (\log \log n)^{ - \frac{\gamma }{2}} } \right)$$
a.s., where {T n } is a sequence of constants such that 1−H(T n )=n −α(logn)β(log logn)γ.
Keywords:
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