求文章两篇

Weighted Semiparametric Estimation in Regression Analysis With Missing Covariate Data
C. Y. Wang, Suojin Wang, Lue-Ping Zhao and Shyh-Tyan Ou
Journal of the American Statistical Association
Vol. 92, No. 438 (Jun., 1997), pp. 512-525
(article consists of 14 pages)
Published by: American Statistical Association
Stable URL: http://www.jstor.org/stable/2965700

Weighted Estimators for Proportional Hazards Regression with Missing Covariates
Lihong Qi, C. Y. Wang and Ross L. Prentice
Journal of the American Statistical Association
Vol. 100, No. 472 (Dec., 2005), pp. 1250-1263
(article consists of 14 pages)
Published by: American Statistical Association
Stable URL: http://www.jstor.org/stable/27590669