Multivariate growth charts and robust quantile estimation

生长图已广泛应用于诊所和医疗中心，以监测个体受试者在人口值背景下的生长或健康状况。目前的增长图表一次只考虑一种衡量标准。研究者建议建立一个多元增长图的框架。更具体地说，拟议研究的目标包括：(1)提供多元增长图的数学形式但临床上合理的定义，并研究其性质；(2)提出估算方法，并将时间效应和其他潜在协变量效应（例如过去的增长）纳入这些增长图表；(3)开发统计推断和模型评估工具；(4)将提出的方法与现有方法进行比较，并探索构建多元增长图的替代方法；(5)提出稳健的分位数估计来限制异常值的影响。在公共卫生和生物医学应用的许多领域，多变量增长图可以提供比目前可用的单变量增长图多得多的信息工具。例如，与单一的身体质量指数（BMI）图表相比，儿科可以通过使用体重和身高纵向信息的多变量方法更好地筛查肥胖。研究人员将开发的方法（如协变量调整多变量分位数函数的估计）是统计研究的普遍兴趣。建议的研究将通过出版物、在国内和国际会议上的演讲以及与临床研究人员的合作广泛传播。

Growth charts have been widely used in clinics and medical centers to monitor an individual subject's growth or health status in context of population values. Current growth charts consider only one measurement at a time. The investigators propose to develop a framework for multivariate growth charts. More specifically, the objectives of the proposed research include (1) to provide a mathematically formal but clinically sensible definition of multivariate growth charts, and study their properties; (2) to propose methodology for estimating and incorporating time effects and other potential covariate effects (e.g. past growth) into those growth charts; (3) to develop statistical inference and model assessment tools; (4) to compare the proposed methodology with existing methods and explore alternative devices for multivariate growth chart construction; (5) to propose robust quantile estimators to limit the impact of outliers. The multivariate growth charts can provide much more informative tools than the currently available univariate growth charts in many areas of public health and biomedical applications. For example, pediatrics will be able to do better screening for obesity with a multivariate approach using longitudinal information on weight and height than with a single body-mass-index (BMI) chart. The methodologies to be developed by the investigators (e.g. estimation of covariate-adjusted multivariate quantile functions) are of general interest to statistical research. The proposed research will be widely disseminated through publications, presentations in domestic and international conferences, and collaborations with clinical researchers.