Past PhD Theses

Browse names and theses by graduation year. If you are an alumna or alumnus of the program, please visit the Alumni Outcomes page to learn more about how to stay involved.

 


2023

Jialu Wang

  • Advocate: Feifang Hu
  • Program: Statistics
  • Thesis Title: Covariate-Adaptive Randomization in Network Data

Yu Xia

  • Advocate: Hua Liang
  • Program: Statistics
  • Thesis Title: Goodness-of-Fit Tests for Several Models

Xiaoyan Yin

  • Advocate: Scott Evans and Toshimitsu Hamasaki
  • Program: Statistics
  • Thesis Title: Sequential Multiple Assignment Randomized Trials for COMparing Personalized Antibiotic StrategieS (SMART COMPASS): Design and Software

Fengyu Zhao

  • Advocate: Feifang Hu
  • Program: Statistics
  • Thesis Title: Statistical Inference of Relative Risk and Hazard Ratio under Covariate Adaptive Randomization

Mengqiu Zhu

  • Advocate: Yinglei Lai
  • Program: Statistics
  • Thesis Title: Some Research Progress in Generative Modeling and the Related Applications to Single-Cell RNA-Sequencing and Spatially Resolved Transcriptomics Data

 


2022

May Al-Husseini

  • Advocate: Qing Pan
  • Program: Biostatistics
  • Thesis Title: Joint Analysis of Adenoma Screening and Colon Cancer Risks with Informative Screening Times

Shuyang Gao

  • Advocate: Hosam Mahmoud
  • Program: Statistics
  • Thesis Title: On Some Classes of Urn Models with Multiple-Drawing

Yufei Guo

  • Advocate: Yinglei Lai
  • Program: Statistics
  • Thesis Title: Evaluation and Prediction of the Association Consistency between Two High-throughput Two-sample Gene Expression Datasets

Bingqi Han

  • Advocate: Yinglei Lai
  • Program: Statistics
  • Thesis Title: Some Research Progress on Generative Adversarial Networks

Xiang Li

  • Advocate: Qing Pan
  • Program: Statistics
  • Thesis Title: Heterogeneous Block Covariance Model for Community Detection

Yang Liu

  • Advocate: Feifang Hu
  • Program: Statistics
  • Thesis Title: Statistical Issues of Unobserved Covariates in Covariate-Adaptive Randomized Trials

Shunyan Luo

  • Advocate: Fang Jin
  • Program: Statistics
  • Thesis Title: Statistically Consistent Interpretation of Deep Learning

Sam Luxenberg

  • Advocate: Sudip Bose and Refik Soyer
  • Program: Statistics
  • Thesis Title: Adversarial Risk Analysis for Decision-Making in Sports

Rui Miao

  • Advocate: Xiaoke Zhang
  • Program: Statistics
  • Thesis Title: Advances in Functional Data Analysis and Reinforcement Learning

Wu Xue

  • Advocate: Xiaoke Zhang
  • Program: Statistics
  • Thesis Title: Methodological Advances in Causal Inference for Functional Daya and Survival Data

Mingze Zhang

  • Advocate: Judy Wang
  • Program: Statistics
  • Thesis Title: Copula-based Analysis for Dependent Count Data

 


2021

Chen Chen

  • Advocate: Yan Ma and Qing Pan
  • Program: Statistics
  • Thesis Title: Meta-analysis of Rare Events

Shiqi Dong

  • Advocate: Zhaohai Li and Aiyi Liu
  • Program: Statistics
  • Thesis Title: On Combination of Elliptically Distributed Biomarkers to Improve Diagnostic Accuracy

Hongfei Du

  • Advocate: Fang Jin
  • Program: Statistics
  • Thesis Title: Uncertainty Quantification and Adversarial Samples Detection of Neural Networks, and Single Reader Between Cases AUC estimator in Nested Data Problem

Yihe Huang

  • Advocate: Yan Ma
  • Program: Biostatistics
  • Thesis Title: Comparison of Machine Learning Methods in Missing Data Imputation for NIS Data

Xiang Peng

  • Advocate: Judy Wang
  • Program: Statistics
  • Thesis Title: Advances in Subgroup Identification and Expected Shortfall Regression

Grecio Sandoval

  • Advocate: Ionut Bebu and John Lachin
  • Program: Biostatistics
  • Thesis Title: On Cost-Efficient Designs for Clinical Studies

 


2020

Lingzhe Guo

  • Advocate: Reza Modarres
  • Program: Statistics
  • Thesis Title: Change Point Detection of Periodic Data

Yuan Gu

  • Advocate: Colin Wu and Hua Liang
  • Program: Biostatistics
  • Thesis Title: Dynamic Conditional Density Models for Multivariate Longitudinal Data

Jinxi Liu

  • Advocate: Naji Younes and Marinella Temprosa
  • Program: Biostatistics
  • Thesis Title: A Joint Model for Survival and Longitudinal Data Using Shape Invariant Models

Shaobo Liu

  • Advocate: Hua Liang
  • Program: Biostatistics
  • Thesis Title: Nonlinear Function-on-Scalar MINQE with Application to Genetic Heritability

Yan Liu

  • Advocate: Zhaohai Li, Barry Graubard, and Kai Yu
  • Program: Biostatistics
  • Thesis Title: Associations via Integrating Analysis of Predicted Expression from Multiple Tissues

Mohamed Megheib

  • Advocate: Sudip Bose
  • Program: Statistics
  • Thesis Title: Nonparametric Regression for Spatially Correlated Data

Peifeng Ruan

  • Advocate: Hua Liang
  • Program: Biostatistics
  • Thesis Title: Advanced Statistical Models in Cancer Research with Omics Data

Arnold Saunders

  • Advocate: Hosam Mahmoud
  • Program: Statistics
  • Thesis Title: Random Recursive Tree Evolution Algorithms: Identification and Characterization of Classes of Deletion Rules

Xiang Shen

  • Advocate: Hua Liang
  • Program: Statistics
  • Thesis Title: Model Averaging of Several Semiparametric Models

Huan Wang

  • Advocate: Qing Pan and Dechang Chen
  • Program: Biostatistics
  • Thesis Title: Development of Prognostic Systems for Cancer Patients

Liuqing Yang

  • Advocate: Qing Pan
  • Program: Statistics
  • Thesis Title: Clustering Models with Applications in Gene Expression Profiles

Xiaoyu Zhai

  • Advocate: Tapan Nayak
  • Program: Statistics
  • Thesis Title: Randomized Response Methods for Privacy Protection in Data Collection and Identification Risk Control in Data Release

Lingjie Zhou

  • Advocate: Qing Pan
  • Program: Statistics
  • Thesis Title: Inverse Weighting Method with Jackknife Variance Estimator for Differential Expression Analysis of Single-cell RNA Sequencing Data

Yifan Zhou

  • Advocate: Feifang Hu
  • Program: Statistics
  • Thesis Title: Some New Advances in Covariate-Adaptive Randomization

 


2019

Jichong Chai

  • Advocate: Tapan K. Nayak, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Privacy Protection in Data Collection via Randomized Response Procedures

Didem Egemen

  • Advocate: Riefik Soyer, Professor of Decision Sciences and Statistics
  • Program: Statistics
  • Thesis Title: Bayesian Modeling of Virtual Age in Repairable Systems

Zhikun Gao

  • Advocate: Huixia Wang, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Automatic Shape-Constrained Nonparametric Regression

Jesse P. Jeter

  • Advocate: Sudip Bose, Associate Professor of Statistics
  • Program: Statistics
  • Thesis Title: Novel Methodologies in Categorical Data Analysis

Fuyuan Li

  • Advocate: Huixia Wang, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Copula-Based Analysis of Dependent Data with Censoring and Zero-Inflation

Xin Li

  • Advocate: Feifang Hu, Professor of Statistics
  • Program: Biostatistics
  • Thesis Title: Interim Analysis in Adaptive Randomized Clinical Trials

Yu Song

  • Advocate: Reza Modarres, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Distribution of Interpoint Distances and Applications

 


2018

Xiaoyu Cai

  • Advocate: Zhaohai Li, Professor of Statistics
  • Co-Advocates: Aiyi Liu, Senior Investigator, National Institutes of Health & Feifang Hu, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Using Proper Transformations to Improve Precision

Somak Chatterjee

  • Advocate: Subrata Kundu, Associate Professor of Statistics
  • Co-Advocate: Rajeshwari Sundaram, Senior Investigator, NICHD/DIPHR
  • Program: Statistics
  • Thesis Title: Joint Modeling of Multiple Skewed Longitudinal Processes with Excess of Zeroes and Time-to-Event Using a Shared Parameter Model

Jie Cong

  • Advocate: Hua Liang, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Nonlinearity Detection Using Penalization-Based Principle

Wenjuan Gu

  • Advocate: Dean Follmann, Assistant Advocate for Biostatistics, National Institute of Allergy and Infectious Diseases
  • Co-Advocate: Naji Younes, Associate Professor of Epidemiology and Biostatistics
  • Program: Biostatistics
  • Thesis Title: Parametric and Semi-parametric Approaches to Estimation of Survival Distributions of Treatment Strategies in Sequential Multiple Assignment Randomized Trials

Yuan Li

  • Advocate: Feifang Hu, Professor of Statistics
  • Co-Advocate: Michael D. Larsen, Professor of Mathematics and Statistics
  • Program: Statistics
  • Thesis Title: Hierarchical Bayesian Model for AK Composite Estimators in the Current Population Survey (CPS)

Cong Wang

  • Advisor: Zhaohai Li
  • Program: Statistics
  • Thesis Title: Analysis for Familial Aggregation Using Recurrence Risk for Complex Survey Data

Fan Wang

  • Advocate: Feifang Hu, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Balancing A Large Number of Covariates via Covariate-Adaptive Randomization

Aotian Yang

  • Advisor: Qing Pan
  • Program: Statistics
  • Thesis Title: Constrained Maximum Entropy Models for Selecting Genotype Interactions Associated with Interval-Censored Failure Times and Methods for Power Calculation in a Three-arm Four-step Clinical Bioequivalence Study

Cheng Zhang

  • Advocate: Tapan K. Nayak, Professor of Statistics
  • Program: Statistics
  • Thesis Title: Identification Risk Control in Microdata Release by Inverse Frequency Post-Randomization and Its Impact on Data Utility

 


2017

    Hailin Huang

    • Advisor: Hua Liang
    • Program: Statistics
    • Thesis Title: Semi-parametric and Structured Nonparametric Modeling

    Biao Yang

    • Advisor: Jonathan Stroud
    • Program: Statistics
    • Thesis Title: Particle and Ensemble Methods for State Space Models

    Li Cheung

    • Advisor: Qing Pan and Hormuzd Katki
    • Program: Statistics
    • Thesis Title: Mixture Models for Left- and Interval-Censored Data and Concordance Indices for Composite Survival Outcomes

    Wanying Zhao

    • Advisor: Feifang Hu
    • Program: Statistics
    • Thesis Title: Adaptive Designs Utilizing Covariates for Precision Medicine and Their Statistical Inference

    Yarong Feng

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: On Fast Growth Models for Random Structures

    Chen Chen

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: Advances in Urn Models and Applications to Self-similar Bipolar Networks

     


    Previous Years

    2016

    Liyi Jia

    • Advisor: Yinglei Lai
    • Program: Statistics
    • Thesis Title: Modeling the Correlation Structure of RNA Sequencing Data Using A Multivariate Poisson-Lognormal Model

    Xing Chen

    • Advisor: Yinglei Lai
    • Program: Statistics
    • Thesis Title: Censored-Poisson Model Based Approach to the Analysis of RNA-seq Data

    Panpan Zhang

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: On Certain Properties of Several Random Networks

    Junchi Guo

    • Advisor: Michael Larsen
    • Program: Statistics
    • Thesis Title: Improvements in Simulation, Convergence Monitoring, and Modeling of the Exponential Random Graph Models for Social Network Analysis

    Brian Dumbacher

    • Advisor: Michael Larsen
    • Program: Statistics
    • Thesis Title: Small Area Estimation in a Survey of Governments

    Xian Sun

    • Advisor: Zhaohai Li and Aiyi Liu
    • Program: Statistics
    • Thesis Title: Diagnostic Accuracy of Biomarkers with a Continuous Gold Standard

    Joshuah Touyz

    • Advisor: Tatiyana Apanasovich
    • Program: Statistics
    • Thesis Title: Novel Methodologies in Multivariate Spatial Statistics
    2015

    Quan Zou

    • Advisor: Zhaohai Li
    • Program: Statistics
    • Thesis Title: The Generalized Relative Pairs IBD Distribution: Its Use in the Detection of Linkage
    2014

    Siyu Qing

    • Advisor: Michael Larson
    • Program: Statistics
    • Thesis Title: Longitudinal Weight Calibration with Estimated Control Totals for Cross Sectional Survey Data: Theory and Application

    Fanni Zhang

    • Advisor: Yinglei Lai
    • Program: Statistics
    • Thesis Title: Concordant Integrative Analysis of Multiple Gene Expression Data Sets

    Mengta Yang

    • Advisor: Reza Modarres
    • Program: Statistics
    • Thesis Title: Depth Functions, Multidimensional Medians and Tests of Uniformity on Proximity Graphs

    Mohammed Chowdhury

    • Advisor: Colin Wu and Reza Modarres
    • Program: Statistics
    • Thesis Title: Nonparametric Smoothing Estimation of Conditional Distribution Function with Longitudinal Data and Time-Varying Parametric Models

    Bipasa Biswas

    • Advisor: Yinglei Lai
    • Program: Biostatistics
    • Thesis Title: Statistical Analysis of DNA Copy Number Variation with Sequencing Data

    Ruihua Xu

    • Advisor: Yinglei Lai and Gang Zheng
    • Program: Biostatistics
    • Thesis Title: Analysis of Mixed Types of Traits in Genetic Association Studies and Application to Genome-Wide Association Studies
    2013

    Wenjing Xu

    • Advisor: Qing Pan and Joseph Gastwirth
    • Program: Statistics
    • Thesis Title: Statistical Properties of Biostatistical Methods for Correlated Processes with Application to Data Arising in the Legal Settings

    Ravi Kalpathy

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: Perpetuities in Fair Leader Election Algorithms

    Jie Zhou

    • Advisor: Zhiwei Zhang and Zhaohai Li
    • Program: Biostatistics
    • Thesis Title: Coarsened Propensity Scores and Hybrid Estimators for Missing Data and Causal Inference

    Marinella Temprosa

    • Advisor: John Lachin
    • Program: Biostatistics
    • Thesis Title: An Imputation-Estimation Algorithm Using Time-Varying Auxiliary Covariates for a Longitudinal Model When Outcome is Missing by Design

    Wenliang Yao

    • Advisor: Zhaohai Li and Barry Graubard
    • Program: Biostatistics
    • Thesis Title: Estimation of the Area Under the ROC Curve With Complex Survey Data

    Wanjie Sun

    • Advisor: Michael Larsen and John Lachin
    • Program: Biostatistics
    • Thesis Title: Methods for a Longitudinal Quantitative Outcome With a Multivariate Gaussian Distribution Multi-dimensionally Censored by Therapeutic Intervention
    2012

    Anna Gordon

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: The Stochastics of Diagnostic and Threat Detection Tests

    Sanaa Kholfi

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: On A Class of Zero-balanced Urn Models

    Mei Jin

    • Advisor: Zhaohai Li and Aiyu Li
    • Program: Statistics
    • Thesis Title: Group Sequential Designs for Intraclass Correlation Coefficients in Reliability Studies

    Donald Bauder

    • Advisor: Sudip Bose
    • Program: Statistics
    • Thesis Title: Bayesian Robustness in Finite Population Testing

    Owen Martin

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: A Dynamic Competing Risk Model for Filtering Reliability and Tracking Survivability
    2011

    John Jackson

    • Advisor: Paul Albert and Zhaohai Li
    • Program: Biostatistics
    • Thesis Title: Prediction Models for Longitudinal Binary and Count Data

    Linglu Wang

    • Advisor: Tapan Nayak
    • Program: Statistics
    • Thesis Title: The Equivariance Criterion in Statistical Prediction and Its Ramifications

    Haojin Zhou

    • Advisor: Paul Albert and Zhaohai Li
    • Program: Biostatistics
    • Thesis Title: Prediction Models for Longitudinal Binary and Count Data

    Tong Zhang

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: Bayesian Analysis of Case-control Genetic Association Studies in the Presence of Population Stratification or Genetic Model

    Samson Adeshiyan

    • Advisor: Tapan Nayak
    • Program: Statistics
    • Thesis Title: Gaussian Phases Toward Statistical Equilibrium in Some Urn Models

    Linglu Wang

    • Advisor: Zhaohai Li and Gang Zheng
    • Program: Biostatistics
    • Thesis Title: Unification of Randomized Response Designs and Certain Aspects of Post-Randomization for Statistical Disclosure Control
    2010

    Anastasios Markitsis

    • Advisor: Yinglei Lai
    • Program: Statistics
    • Thesis Title: The Proportion of True Null Hypotheses in Microarray Gene Expression Data

    Zhenyu Liu

    • Advisor: Reza Modarres
    • Program: Statistics
    • Thesis Title: Triangle Test and Triangle Data Depth in Nonparametric Multivariate Analysis

    Min Qin

    • Advisor: Tapan Nayak
    • Program: Statistics
    • Thesis Title: Some Contributions to the Theory of Unbiased Statistical Prediction

    Mark Tripputi

    • Advisor: John Kittelson and Zhaohai Li
    • Program: Statistics
    • Thesis Title: Use of Mediation in Designing Clinical Trials with Two Primary End Points

    Dewei She

    • Advisor: Zhaohai Li
    • Program: Statistics
    • Thesis Title: Genetic Association Studies Using Complex Survey Data

    Susan Warren

    • Advisor: Karen Bandeen-Roche and Samuel J. Simmensi
    • Program: Statistics
    • Thesis Title: Evaluating the Value of Adding Diagnostic Symptoms Using Posterior Probability and Sensitivity/Specificity Procedures
    2009

    Hiroyuki Hikawa

    • Advisor: Joseph .L.Gastwirth and E.Bura
    • Program: Statistics
    • Thesis Title: Local Linear Peters-Belson Regression and Its Applications to Employment Discrimination Cases

    Lihan Yan

    • Advisor: Zhaohai Li and Gang Zheng
    • Program: Statistics
    • Thesis Title: Group Sequential Robust Designs in Genetic Studies
    2008

    Mark VanRaden

    • Advisor: John Lachin
    • Program: Statistics
    • Thesis Title: Cumulative Logit-Poisson and Cumulative Logit-Negative Compound Regression Models for Count Data

    Ruththanna Davi

    • Advisor: John Lachini
    • Program: Statistics
    • Thesis Title: Cumulative Logit-Poisson and Cumulative Logit-Negative Compound Regression Models for Count Data

    Dalong Huang

    • Advisor: Zhaohai Li and Joseph L. Gastwirth
    • Program: Statistics
    • Thesis Title: Effects of Contamination on Statistical Inference Using Sib-Pair Analysis
    2007

    Yu Shu

    • Advisor: Zhaohai Li and Aiyi Liu
    • Program: Biostatistics
    • Thesis Title: Group sequential designs and inference of a medical diagnostic test with binary outcomes

    Jiao Yang

    • Advisor: Efstathia Bura
    • Program: Statistics
    • Thesis Title: Statistical Methods for Estimating the Dimension of Multivariate Data

    Philip Wilson

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: On the Utility of Reliability

    Joshua Landon

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: A Problem in Particle Physics and its Bayesian Analysis
    2006

    Xiaowu Chen

    • Advisor: Zhaohai Li
    • Program: Biostatistics
    • Thesis Title: AInference of Haploytepe Effects in Case-Control Studies Using Unphased Genotype and Environmental Data

    Ainong Zhou

    • Advisor: Giovanni Parmigiani and John M Lachini
    • Program: Biostatistics
    • Thesis Title: Bayes Factors Comparing Two Multi-Normal Covariance Matrices and their Application to Microarray Data Analysis

    Konstantin Gartwig

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: Asset pricing under parameter uncertainty
    2005

    Dennis Buckman

    • Advisor: Zhaohai Li
    • Program: Biostatistics
    • Thesis Title: Linkage Tests for Relative-Pairs with Incomplete IBD and Known IBS

    Weiping Deng

    • Advisor: Zhaohai Li
    • Program: Statistics
    • Thesis Title: Mixture models and their properties for interval mapping of genetic loci affecting binary traits

    Terrence Hui

    • Advisor: Reza Modarres
    • Program: Statistics
    • Thesis Title: Bootstrap and likelihood based inference for ranked set samples

    Barbara George

    • Advisor: Kaushik Ghosh
    • Program: Biostatistics
    • Thesis Title: Bayesian Regression for Circular Data
    2004

    Jiaquan Fan

    • Advisor: Kaushik Ghosh
    • Program: Statistics
    • Thesis Title: Short-term cancer incidence prediction with missing data

    Costas Christophi

    • Advisor: Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: Distances in Random Tries via Analytic Probability: The Oscillatory Distribution

    Abeer El-Baz

    • Advisor: Tapan Nayak
    • Program: Statistics
    • Thesis Title: Some contributions to statistical prediction theory
    2003

    Pablo Bonangelino

    • Advisor: Thomas Louis and John M Lachin
    • Program: Biostatistics
    • Thesis Title: Maximin Efficiency Robust Tests for the Focused Clustering of Disease

    Jinyu Yuan

    • Advisor: Joseph L. Gastwirth and Zhaohai Li
    • Program: Statistics
    • Thesis Title: Statistical studies on genetic linkage analysis based on affected Sibships

    Jade Freeman

    • Advisor: Reza Modarres
    • Program: Statistics
    • Thesis Title: An analysis of Box-Cox Transformed Data
    2002

    Yvonne Sparling

    • Advisor: John M Lachin and Naji Younes
    • Program: Biostatistics
    • Thesis Title: Parametric Survival Models for Interval-Censored Data with Time-Dependent Covariates
    2001

    Xuejun Chen

    • Advisor: Zhaohai Li
    • Program: Statistics
    • Thesis Title: The estimation and asymptotic theory of multiplicative Frailty model

    Christopher Moriarity

    • Advisor: Fritz Scheuren and Tapan Nayak
    • Program: Statistics
    • Thesis Title: Statistical properties of statistical matching

    Kimberly Sellers

    • Advisor: Nozer Singpurwalla
    • Program: Statistics
    • Thesis Title: Vague coherent systems

    Binbing Yu

    • Advisor: Joseph L. Gastwirth
    • Program: Statistics
    • Thesis Title: Some problems arising in observational studies: Potential effect of selection bias and omitted variables

    James Cantor

    • Advisor: David Findley and Hosam Mahmoud
    • Program: Statistics
    • Thesis Title: Recursive and batch estimation of misspecified ARMA model
    2000

    Chenxiong Le

    • Advisor: James Rochon
    • Program: Statistics
    • Thesis Title: Application of ARCH models to the analysis of longitudinal data

    Jun Li

    • Advisor: Isabelle Bajeux-Besnainou and Sudip Bose
    • Program: Statistics
    • Thesis Title: A stochastic volatility model for option pricing

    Tirso Diaz

    • Advisor: Robert Smythe and John Lachin
    • Program: Statistics
    • Thesis Title: Simultaneous testing and estimation of trend in proportion using historical data

    Gang Zheng

    • Advisor: Joseph L. Gastwirth
    • Program: Statistics
    • Thesis Title: Fisher information in order statistics and ordered randomly censored data