分位数误差校正模型及应用

误差校正模型具有较好的预测能力,在时间序列分析中占据重要地位。将误差校正模型从均值框架推广到分位数框架,提出了分位数误差校正模型的概念,并给出一整套建模技术：模型表示、参数估计、模型定阶、诊断检验、密度预测等。通过数值模拟,将其与经典的均值误差校正模型、分位数自回归模型进行比较,发现分位数误差校正模型极大地提高了预测的准度与精度。此外,选取中国货币供应与物价水平之间关系作为研究对象,实证检验了分位数误差校正模型的条件密度预测能力。     

一个新的时变系数分位数回归模型及应用

结合普通分位数回归的模型结构和可行性最小二乘方法的时变系数特征,在普通分位数回归模型的损失函数中引入动态误差设定,提出了一个新的模型：时变系数分位数回归模型,并给出其模型表示、模型估计以及模型检验等建模方法。时变系数分位数回归模型更能够适应广泛数据类型的建模需求,体现回归系数的时变特征,揭示解释变量对响应变量完整条件分布特征的影响,具有广阔的应用前景。将其应用于组合投资决策分析,构造出VaR风险动态组合投资方案,并与VaR风险静态组合投资方案、方差风险静态组合投资方案、方差风险动态组合投资方案等进行实证比较。结果表明,基于时变系数分位数回归模型的VaR风险动态组合投资方案所得投资效果在收益、方差、Sharpe比率和VaR数值等方面都显著优于其他三种方案。     

门限分位数自回归模型的预测方法及应用

金融经济系统预测是宏观经济管理的重要问题,系统中大多数变量具有非线性与异质性等特征,门限分位数自回归（TQAR）模型能够较好地揭示这一特征。本文研究TQAR模型的预测技术,给出其条件分位数预测和条件密度预测方法。数值模拟结果表明,与传统的门限均值自回归模型（TAR）和分位数自回归（QAR）模型相比,TQAR模型在预测的精度和准度方面更具优势。文章使用TQAR模型研究中国通货膨胀的非线性动态特征,并在此基础上预测通货膨胀的波动趋势。实证结果表明,TQAR模型不仅能够揭示通货膨胀的门限效应和异质效应,提供比TAR和QAR模型更高的预测精准度,而且能够通过条件密度预测曲线,细致刻画通货膨胀条件分布的位置、散布与形状等全景信息,从而为宏观经济政策的制定和调整提供科学合理的决策依据。     

前瞻性利率规则在我国的实证研究——基于分位数回归方法的变参数检验

本文通过引入预期货币供给增长变量,设定了一个符合我国现实国情的前瞻性利率规则,利用分位数回归方法对该前瞻性利率规则进行实证检验后发现,前瞻性利率规则能够保证我国经济运行在偏离均衡状态或央行目标时采取正确的政策调整方向,保证经济运行的稳定性。具体而言,预期货币供给增长率响应系数随着利率由条件分布的低端向高端变动而呈现单向递增的变化趋势,而预期通胀和预期产出缺口的响应系数变化趋势并非是单向的,分别呈现先增后减和先减后增的变化趋势。     

基于波动率的货币与产出关系检验——来自分位数回归模型的新证据

本文使用1991年1月到2012年3月的样本数据对货币波动率和实际产出波动率之间的关系进行了检验。首先,应用GARCH模型度量货币波动率和产出波动率,进而对二者进行了Granger因果关系检验,发现我国货币供给增长率及其波动率对实际产出增长率及其波动率具有解释和预测能力。其次,使用分位数回归模型研究产出波动率在较小(低分位数)和较大(高分位数)时对货币供给量M0和M1波动率的不同反应程度。最后,提出了稳定产出增长,防止产出剧烈波动的货币政策建议。     

教育和经验对中国居民收入的影响——基于分位数回归和审查分位数回归的实证研究

本文主要用较为前沿的分位数回归以及审查分位数回归技术对中国的明瑟方程进行检验,结果表明,教育和经验对于中国居民的收入有正面的促进作用,教育的回报率似乎随着收入的增加而下降,而经验的回报率似乎随着收入的增加而上升。文章还比较了教育和经验在不同的分位点对于中国男性居民和女性居民各自的影响,结果发现在各个分位点上,教育和经验对中国女性居民收入的回报要高于对男性居民收入的回报。本文还比较了一下普通分位数回归结果与审查分位数回归结果,发现当被解释变量右端受到审查时,在较低的分位点上,两者之间的估计结果是一样的,而在较高的分位点上,两者的估计结果明显不同。     

无条件分位数处理效应方法及其应用

研究目标：政策评估在我国经济社会研究中备受关注,但所采用的方法以平均处理效应居多,分位数处理效应鲜见。与后者相关的理论和应用研究与国外尚存在较大差距,亟待跟进。研究方法：采用蒙特卡罗模拟方法比较了条件分位数处理效应（CQTE）与UQTE方法和其他UQTE方法之间的异同。研究发现：如果回归中只包含常数项和处理变量,CQTE与UQTE是等价的;如果个体在处理组和控制组中的相对位置保持不变,CQTE和UQTE都可以得到无偏估计。研究创新：通过最低工资标准提升政策对居民工资分布影响的实例说明UQTE方法在政策评价中的应用。研究价值：基于断点回归和双差分模型对新的UQTE拓展方法进行探索性展望。     

基于Delta-Gamma-Theta-Cornish-Fisher模型的外汇期权风险度量

本文引入金融参数Delta、Gamma、Theta，将外汇期权近似表达式拓展成Delta-Gamma-Theta模型(简称DGT模型)，且运用Cornish-Fisher方法来调整置信区间，以校正Delta-Gamma-Theta风险对正态分布偏斜的影响，就可近似地得到分位数，从而估计出VaR值与基于Delta正态分布模型、Monte-Carlo模拟进行了比较，结果表明此模型是一个比较好的度量外汇期权风险的方法和工具。     

外汇储备非均衡分析框架——中国最优外汇储备规模测算

从外汇储备短期非均衡是一种常态的角度出发，同时引入货币学说的观点，构造外汇储备动态调整模型，通过实际外汇储备量来估计调整系数，通过套算算出决定最优外汇储备规模各变量系数，即推导出一个经济体最优外汇储备规模需求函数。实证结果显示：我国实际外汇储备规模大于本文模型测算的最优外汇储备量。     

通货膨胀持久性及其非对称性研究——基于分位数自回归模型

本文运用分位数自回归模型研究中国通胀率的持久性及其非对称性特征.研究结果表明,中国通胀率具有高持久性,从通胀率条件分布的低分位数到高分位数,持久性不断增强.基于不同分位数的单位根检验结果显示,中国的通胀持久性具有非对称性,即在受到负向冲击或减速通胀状态下,通胀率序列往往服从平稳自回归过程;而在受到正向冲击或加速通胀状态下,通胀率序列通常服从单位根过程.分位数自回归模型可以有效区分通胀率波动路径中的平稳点和非平稳点.据此,央行可以构建预警机制,以对通胀率的波动进行实时监测和调控.     

Conditional empirical likelihood estimation and inference for quantile regression models

This paper considers two empirical likelihood-based estimation, inference, and specification testing methods for quantile regression models. First, we apply the method of conditional empirical likelihood (CEL) by Kitamura et al. [2004. Empirical likelihood-based inference in conditional moment restriction models. Econometrica 72, 1667–1714] and Zhang and Gijbels [2003. Sieve empirical likelihood and extensions of the generalized least squares. Scandinavian Journal of Statistics 30, 1–24] to quantile regression models. Second, to avoid practical problems of the CEL method induced by the discontinuity in parameters of CEL, we propose a smoothed counterpart of CEL, called smoothed conditional empirical likelihood (SCEL). We derive asymptotic properties of the CEL and SCEL estimators, parameter hypothesis tests, and model specification tests. Important features are (i) the CEL and SCEL estimators are asymptotically efficient and do not require preliminary weight estimation; (ii) by inverting the CEL and SCEL ratio parameter hypothesis tests, asymptotically valid confidence intervals can be obtained without estimating the asymptotic variances of the estimators; and (iii) in contrast to CEL, the SCEL method can be implemented by some standard Newton-type optimization. Simulation results demonstrate that the SCEL method in particular compares favorably with existing alternatives.     

Partial cross-quantilogram networks: Measuring quantile connectedness of financial institutions

We propose partial cross-quantilogram networks for measuring the connectedness of 30 China’s financial institutions at different quantiles. We find that networks at the extreme quantiles are more closely connected than those at the median quantile. The network density and centrality show that the systemically important financial institutions vary across different quantiles. We observe an asymmetric effect in quantile connectedness during the period of “2015–16 Chinese stock market turbulence;” that is, the network connectedness at the lower quantile (i.e., 0.05 quantile) is higher than that at the upper and median quantiles (i.e., 0.95 and 0.50 quantiles). By analyzing the similarity of networks across quantiles, we find that the similarity index is relatively high in the crisis period. Our study provides useful information on connectedness of financial institutions for regulators and investors.     

Analyzing quantile spillover effects among international financial markets

This paper investigates the quantile-based spillover effects among 17 stock markets from January 1993 to January 2022, utilizing a quantile approach based on the variance decomposition of a quantile vector autoregression (QVAR) model. Compared with the traditional mean-based spillover measures, this new quantile approach allows for a nuanced investigation of spillovers at every quantile and capture spillovers under extreme events. The results show that: (1) the total spillover is high and exhibits strong time-varying characteristics, and the tail spillover is higher and more complex in scale and direction; (2) the spillover at each quantile level shows an upward trend, especially during the 2008 crisis and the COVID-19 epidemic; (3) developed countries (or regions) are the net exporters of stock market spillovers, while the developing countries are the net importers; and (4) the 17 stock markets constitute different local financial networks, which may be related to economic conditions and geographical location.     

带未知异方差与半线性结构Tobit模型的半参数估计

本文将Tobit模型扩展至同时带未知条件异方差与半线性结构回归函数的场合,并提出一种计算简便的半参数二步估计法。该方法的关键之处在于连续两次施以成对相减变换,并先后消去第一步所得被解释变量非参数条件分位函数中的两类非线性冗余成分(非线性回归函数部分与未知异方差结构)。文章证明了估计量的n-一致性与渐近正态性,并通过Monte Carlo模拟研究了分位点对的选择、扰动项分布类型与样本删尾程度等因素对估计量小样本性质的影响。最后通过国内居民医疗服务利用不平等的实例验证了本文所提的方法。     

Quantile cointegrating regression

Quantile regression has important applications in risk management, portfolio optimization, and asset pricing. The current paper studies estimation, inference and financial applications of quantile regression with cointegrated time series. In addition, a new cointegration model with quantile-varying coefficients is proposed. In the proposed model, the value of cointegrating coefficients may be affected by the shocks and thus may vary over the innovation quantile. The proposed model may be viewed as a stochastic cointegration model which includes the conventional cointegration model as a special case. It also provides a useful complement to cointegration models with (G)ARCH effects. Asymptotic properties of the proposed model and limiting distribution of the cointegrating regression quantiles are derived. In the presence of endogenous regressors, fully-modified quantile regression estimators and augmented quantile cointegrating regression are proposed to remove the second order bias and nuisance parameters. Regression Wald tests are constructed based on the fully modified quantile regression estimators. An empirical application to stock index data highlights the potential of the proposed method.     

Estimating structural changes in regression quantiles

This paper considers the estimation of multiple structural changes occurring at unknown dates in one or multiple conditional quantile functions. The analysis covers time series models as well as models with repeated cross-sections. We estimate the break dates and other parameters jointly by minimizing the check function over all permissible break dates. The limiting distribution of the estimator is derived and the coverage property of the resulting confidence interval is assessed via simulations. A procedure to determine the number of breaks is also discussed. Empirical applications to the quarterly US real GDP growth rate and the underage drunk driving data suggest that the method can deliver more informative results than the analysis of the conditional mean function alone.     

A new quantile treatment effect model for studying smoking effect on birth weight during Mother's pregnancy

This paper proposes a new quantile regression model to characterize the heterogeneity for distributional effects of maternal smoking during pregnancy on infant birth weight across different the mother's age. By imposing a parametric restriction on the quantile functions of the potential outcome distributions conditional on the mother's age, we estimate the quantile treatment effects of maternal smoking during pregnancy on her baby's birth weight across different age groups of mothers. The results show strongly that the quantile effects of maternal smoking on low infant birth weight are negative and substantially heterogenous across different ages.     

Inference on endogenously censored regression models using conditional moment inequalities

Under a quantile restriction, randomly censored regression models can be written in terms of conditional moment inequalities. We study the identified features of these moment inequalities with respect to the regression parameters where we allow for covariate dependent censoring, endogenous censoring and endogenous regressors. These inequalities restrict the parameters to a set. We show regular point identification can be achieved under a set of interpretable sufficient conditions. We then provide a simple way to convert conditional moment inequalities into unconditional ones while preserving the informational content. Our method obviates the need for nonparametric estimation, which would require the selection of smoothing parameters and trimming procedures. Without the point identification conditions, our objective function can be used to do inference on the partially identified parameter. Maintaining the point identification conditions, we propose a quantile minimum distance estimator which converges at the parametric rate to the parameter vector of interest, and has an asymptotically normal distribution. A small scale simulation study and an application using drug relapse data demonstrate satisfactory finite sample performance.     

带多个变点的逐段连续线性分位数回归模型及应用

研究目标：建立具有多个变点的逐段连续线性分位数回归模型（Continuous Piecewise Linear Quantile Regression with Multiple Change Points,CPLQR）。研究方法：先通过LASSO和广义贝叶斯信息准则确定变点个数,再通过线性化技巧来估计变点的位置与回归系数。研究发现：新方法能够同时确定变点个数、估计变点位置和回归系数,而且具有较强的稳健性;应用该方法于年龄和身体质量指数之间关系,进一步证实了模型的实用性。研究创新：新方法能够处理多个变点的问题,通过LASSO和广义贝叶斯信息准则确定变点数目,避免了主观判断的弊端;借助线性化技巧,解决了目标函数在变点处不可导问题。研究价值：本文结果将为分析经济、金融、医药和生物等学科中存在结构变化的数据提供强有力的研究工具。