Automated selection of post‐strata using a model‐assisted regression tree estimator

Despite having desirable properties, model‐assisted estimators are rarely used in anything but their simplest form to produce official statistics. This is due to the fact that the more complicated models are often ill suited to the available auxiliary data. Under a model‐assisted framework, we propose a regression tree estimator for a finite‐population total. Regression tree models are adept at handling the type of auxiliary data usually available in the sampling frame and provide a model that is easy to explain and justify. The estimator can be viewed as a post‐stratification estimator where the post‐strata are automatically selected by the recursive partitioning algorithm of the regression tree. We establish consistency of the regression tree estimator and a variance estimator, along with asymptotic normality of the regression tree estimator. We compare the performance of our estimator to other survey estimators using the United States Bureau of Labor Statistics Occupational Employment Statistics Survey data.     

Projecting future utilization of medically assisted fertility treatments

This study estimates the future utilization of medically assisted fertility treatments in Australia, focusing on assisted reproductive technologies (ARTs), intrauterine insemination (IUI), and ovulation induction. A multistate cohort component population projection model is used to determine future fertility rates from 2016 to 2026 by age and education level. These are combined with information on recent trends in use and success rates to indirectly estimate future age-specific probabilities of fertility treatment utilization. The number of ART cycles is expected to increase by 61 per cent between 2016 and 2026 if treatment success rates remain at 2015 levels, or by 34 per cent if recent improvements in ART success rates continue. The model also predicts that numbers of IUI cycles and ovulation induction cycles will decrease by 17 and 3 per cent, respectively. This research confirms the importance of including both technological improvements and socio-demographic changes when predicting future fertility treatment utilization.     

计算机辅助教学的应用前景及应用原则

计算机辅助教学是现代化教育技术的核心内容 ,有着巨大的生命力和广阔的应用前景。作者在教改实践中对物理教学手段的现代化问题进行了探讨 ,得出了计算机辅助教学优于传统的教学手段的结论 ,同时认识到 ,在制作CAI课件时必须以教学的优化为终极目标 ,并遵循教学适用性原则     

充分发挥CAI在现代教学中的作用

计算机辅助教学 (CAI)在现代教育中发挥着越来越大的作用。论述了国内 CAI发展的历程 ,重点介绍了 CAI的基本模式 ,即练习式、课堂教学辅导式、情境建构式、网络学习式的特点 ;分析了 CAI课件的结构类型 ,主要有直线型、分枝型、可编辑型、智能型 ,并阐述了 CAI课件的开发过程     

Réduction de la variance dans les sondages en présence d'information auxiliarie: Une approache non paramétrique par splines de régression

The author considers the use of auxiliary information available at population level to improve the estimation of finite population totals. She introduces a new type of model‐assisted estimator based on nonparametric regression splines. The estimator is a weighted linear combination of the study variable with weights calibrated to the B‐splines known population totals. The author shows that the estimator is asymptotically design‐unbiased and consistent under conditions which do not require the superpopulation model to be correct. She proposes a design‐based variance approximation and shows that the anticipated variance is asymptotically equivalent to the Godambe‐Joshi lower bound. She also shows through simulations that the estimator has good properties.     

物理类CAI课件的设计和评价

本文结合实际，阐述了课件的各项设计，讨论了课件的开发过程。     

φ16cm宽束离子源的设计

本文介绍了一种口径为φ１６ｃｍ的宽束离子源的设计．该源采用了多极场型放电室，结构紧凑合理，便于清洁维修以及更换离子引出系统．使用二栅引出系统时，可获得５０～１５００ｅＶ的离子束．距源１０ｃｍ处，５００ｅＶ的氩离子束的束流密度可达０．９５ｍＡ／ｃｍ２，且±８％均匀性的均匀区域达φ１４ｃｍ．     

Housing for Older People in Iceland: Apartments and Nursing Homes

The first residential and nursing homes in Iceland were built in the early 1920s, and the first apartments for older people in the early 1970s. Most of the existing housing for older persons was built in the last 30 years. Legislative provisions on housing and particularly on assisted living have not changed significantly since laws relating to the affairs of the elderly were first passed in 1983. While approximately 90% of older people in Iceland own their own home and the primary stated goal of the government is to support independent living, official policy relies on placement in nursing homes. Services and care at home, provided by social and home healthcare services, has not been developed to the same extent as in the other Nordic countries. Clearer guidelines on integrated service housing are needed to reach the government's primary stated goal. Placing more emphasis on delivering services, care, and rehabilitation to people living in the community could shorten individuals’ length of stay in hospitals, delay admission to nursing homes, and better meet the expectations of older people for independent living.     

Assisted Workouts: Starting My Own Workout Program

Abstract

As an undergraduate student with cerebral palsy, I found it difficult to achieve my goal of starting a regular exercise program at my school, the University of Central Florida. However, when I started a program called Assisted Workouts in spring 2003, the struggle proved to be well worth it. The program is not only beneficial to me, but it has also opened the door for other students who, because of disability or injury, need assistance in using gym equipment.     

不定方程与计算机辅助教学

在不定方程教学中，如果辅之以计算机教学，将会得到良好的教学效果．文中的几个程序实例，运行的实际结果能够反映计算机辅助教学的作用．