Finite Sample Properties of the Two-Step Empirical Likelihood Estimator

ABSTRACT

We investigate the finite sample properties of two-step empirical likelihood (EL) estimators. These estimators are shown to have the same third-order bias properties as EL itself. The Monte Carlo study provides evidence that (i) higher order asymptotics fails to provide a good approximation in the sense that the bias of the two-step EL estimators can be substantial and sensitive to the number of moment restrictions and (ii) the two-step EL estimators may have heavy tails.     

Estimating Long and Short Run Effects in Static Panel Models

Abstract

This paper assesses the biases of four different estimators with respect to the short run and the long run parameters if a static panel model is used, although the data generating process is a dynamic error components model. We analytically derive the associated biases and provide a discussion of the determinants thereof. Our analytical and numerical results as well as Monte Carlo simulations illustrate that the asymptotic bias of both the within and the between parameter with respect to the short run and long run impact can be substantial, depending on the memory of the data generating process, the length of the time series and the importance of the cross-sectional variation in the explanatory variables.     

Perception,Preference, and Patriotism: An Exploratory Analysis of the 1980 Winter Olympics

This article analyzes scores given by judges of figure skating at the 1980 Winter Olympics. Judges' scores are found to be highly correlated, with little evidence of scoring along political lines. However, an analysis of variance shows a small but consistent “patriotic” bias; judges tend to give higher scores to contestants from their own country. The influence of such effects on final placings is estimated.     

意见的公共表达:公共争议的传播偏向与话语民主化

公共争议是世界性的社会现象与文化存在。公共争议传播中,去公共性的叙事偏向与话语困境,背离公共争议公共性的诉求。公共争议传播中,意见的公共表达,需要大众媒介以公共性的诉求为主导,透过对话解释性叙事以及话语的民主化,动员社会资源,走向公共参与,回归公共争议传播公共性的诉求。     

电视新闻与社教节目的品质研制:中部四省例证

节目品质是评判广电媒体公共服务表现的根本标准。研究发现新闻节目存在"结构性紧缺"的问题而不能满足公众的知情需要;社教节目因节目产制的"结构性偏向",处于资源配置的弱势,造成节目内容缺少文化品位和思想深度,而限制了公共服务功能的发挥。下一步,要明确公共服务作为的方向,建立节目品质评价机制来推动电视回归其政治和文化属性。     

VOA新闻报道对中国偏见的语用分析

由于政治、经济、文化、意识形态等方面的因素,VOA关于中国的新闻报道存在明显的新闻偏见,给以VOA为语言学习载体的中国英语学习者带来困惑和误导。文章从语用学的视角,就词汇运用、修辞方法、篇章结构三个层面分析了新闻偏见的具体表现形式,指出中国英语学习者应以批判的眼光从VOA学习英语语言知识和了解西方文化,避免因新闻偏见的误导而影响语言学习效果。     

Social assistance assessments of couple households: A vignette study on applicants’ ethnicity and gendered family roles

Social work professionals’ assessments of social assistance (SA) eligibility for a heterosexual couple with a baby are examined. Professionals (n = 899) spread over 43 social service offices in 19 Swedish municipalities assessed a vignette. According to the vignette, one of the parents abstained from paid work to take parental leave, which caused the couple's need for SA. Two vignette dimensions were varied: the couple's ethnicity (Swedish/Arabic) and gendered family roles (mother/father going on parental leave). Data were analysed using multilevel logistic regression modelling. The results show that the combination of the couple's gendered family roles and ethnicity seems to have bearing on the assessments. Professionals were most prone to grant SA to couples with Swedish names where the mother went from work to parental leave. The lowest granting rate was found in assessments of couples with the same gender setting and Arabic names.     

A meta-analytic framework to adjust for bias in external control studies

While randomized controlled trials (RCTs) are the gold standard for estimating treatment effects in medical research, there is increasing use of and interest in using real-world data for drug development. One such use case is the construction of external control arms for evaluation of efficacy in single-arm trials, particularly in cases where randomization is either infeasible or unethical. However, it is well known that treated patients in non-randomized studies may not be comparable to control patients—on either measured or unmeasured variables—and that the underlying population differences between the two groups may result in biased treatment effect estimates as well as increased variability in estimation. To address these challenges for analyses of time-to-event outcomes, we developed a meta-analytic framework that uses historical reference studies to adjust a log hazard ratio estimate in a new external control study for its additional bias and variability. The set of historical studies is formed by constructing external control arms for historical RCTs, and a meta-analysis compares the trial controls to the external control arms. Importantly, a prospective external control study can be performed independently of the meta-analysis using standard causal inference techniques for observational data. We illustrate our approach with a simulation study and an empirical example based on reference studies for advanced non-small cell lung cancer. In our empirical analysis, external control patients had lower survival than trial controls (hazard ratio: 0.907), but our methodology is able to correct for this bias. An implementation of our approach is available in the R package ecmeta .     

Left truncation in linked data: A practical guide to understanding left truncation and applying it using SAS and R

Time-to-event data such as time to death are broadly used in medical research and drug development to understand the efficacy of a therapeutic. For time-to-event data, right censoring (data only observed up to a certain point of time) is common and easy to recognize. Methods that use right censored data, such as the Kaplan–Meier estimator and the Cox proportional hazard model, are well established. Time-to-event data can also be left truncated, which arises when patients are excluded from the sample because their events occur before a specific milestone, potentially resulting in an immortal time bias. For example, in a study evaluating the association between biomarker status and overall survival, patients who did not live long enough to receive a genomic test were not observed in the study. Left truncation causes selection bias and often leads to an overestimate of survival time. In this tutorial, we used a nationwide electronic health record-derived de-identified database to demonstrate how to analyze left truncated and right censored data without bias using example code from SAS and R.     

No mood effects in the field: The case of car inspections

We study mood effect in the field to measure its economic impact and address shortcomings in the existing literature, which typically uses one single mood proxy and ignores selection effects. Using over 50 million car inspections in Sweden and England and multiple mood proxies, we study whether car inspectors are more lenient on good mood days and if car owners self-select into those days. We find evidence of a “Friday effect” in England and a small selection bias, but no support for consistent mood effect. Our findings highlight the importance of considering the expectations of rational actors who may exploit mood effect and the need to study mood in the field using different settings and multiple proxies to avoid hasty conclusions.