人力资本、FDI技术溢出与区域自主创新——基于空间计量模型的实证研究

通过运用空间计量经济模型,对2005—2009年的省际数据进行分析来检验人力资本与FDI技术溢出对区域自主创新的影响。结果表明,在样本期内人力资本与FDI均对我国自主创新有较显著的促进作用,且人力资本的提高有助于对FDI所带来的国外技术的吸收。同时发现,我国各地区间的技术创新能力呈现出显著的空间自相关性,因而采用空间计量经济模型来估计变量间的关系比经典回归模型更为稳健可靠。     

Time-varying risk in the German stock market

This paper compares two specifications of the Capital Asset Pricing Model for a sample of German stocks. The specifications generate time-varying first and second moments by conditioning on past information. This explicit modelling of the time series behaviour of risk allows us to characterize the driving factors of variances and covariances of returns. In addition to a variety of diagnostic tests we evaluate the validity of the one-factor restriction in the CAPM. The main findings are that risk is time dependent and very variable and also that more than one factor is needed to fit the data set.     

Portfolio Returns,Market Volatility,and Seasonality

This paper examines three important issues related to the relationship between stock returns and volatility. First, are Duffee's (1995) findings of the relationship between individual stock returns and volatility valid at the portfolio level? Second, is there a seasonality of the market return volatility? Lastly, do size portfolio returns react symmetrically to the market volatility during business cycles? We find that the market volatility exhibits strong autocorrelation and small size portfolio returns exhibit seasonality. However, this phenomenon is not present in large size portfolios. For the entire sample period of 1962–1995, the highest average monthly volatility occurred in October, followed by November, and then January. Examining the two sub-sample periods, we find that the average market volatility increases by 15.4% in the second sample period of 1980–1995 compared to the first sample period of 1962–1979. During the contraction period, the average market volatility is 60.9% higher than that during the expansion period. Using a binary regression model, we find that size portfolio returns react asymmetrically with the market volatility during business cycles. This paper documents a strongly negative contemporaneous relationship between the size portfolio returns and the market volatility that is consistent with the previous findings at the aggregate level, but is inconsistent with the findings at the individual firm level. In contrast with the previous findings, however, we find an ambiguous relationship between the percentage change in the market volatility and the contemporaneous stock portfolio returns. This ambiguity is attributed to strongly negative contemporaneous and one-month ahead relationships between the market volatility and portfolio returns.

     

客户型文化促进了企业创新吗?——来自中国制造业上市公司的经验证据

客户型文化是市场经济环境下企业重要的文化维度,是企业内部控制环境的组成部分,促使企业和客户之间的隐性契约得到较好地履行,有利于合作创新的开展.文章对客户型文化促进企业创新进行理论分析,并以2010-2017年A股制造业上市公司作为样本,实证检验了企业客户型文化对创新绩效的影响以及其中的中介路径.研究结果表明:(1)企业客户型文化对企业专利申请数有明显的促进作用;(2)降低大客户的波动性、增加客户的异质性和缓解企业的融资约束是客户型文化促进企业创新的中介路径.     

S&P 500 implied volatility and monetary policy announcements

While many studies have investigated the link between macroeconomic events and equity market volatility, few have considered the impact on option implied volatilities. Given the recent focus on trading in implied volatility, in the context of the S&P 500 VIX index, this paper examines how the VIX index behaves around US monetary policy announcements. It is revealed that the VIX index falls significantly on the day of Federal Open Market Committee meetings.     

Moment explosions in stochastic volatility models

In this paper, we demonstrate that many stochastic volatility models have the undesirable property that moments of order higher than 1 can become infinite in finite time. As arbitrage-free price computation for a number of important fixed income products involves forming expectations of functions with super-linear growth, such lack of moment stability is of significant practical importance. For instance, we demonstrate that reasonably parametrized models can produce infinite prices for Eurodollar futures and for swaps with floating legs paying either Libor-in-arrears or a constant maturity swap rate. We systematically examine the moment explosion property across a spectrum of stochastic volatility models. We show that lognormal and displaced-diffusion type models are easily prone to moment explosions, whereas CEV-type models (including the so-called SABR model) are not. Related properties such as the failure of the martingale property are also considered.

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Maximum likelihood estimation of the double exponential jump-diffusion process

The double exponential jump-diffusion (DEJD) model, recently proposed by Kou (Manage Sci 48(8), 1086–1101, 2002) and Ramezani and Zeng (http://papers.ssrn.com/sol3/papers.cfm?abstract_id=606361, 1998), generates a highly skewed and leptokurtic distribution and is capable of matching key features of stock and index returns. Moreover, DEJD leads to tractable pricing formulas for exotic and path dependent options (Kou and Wang Manage Sci 50(9), 1178–1192, 2004). Accordingly, the double exponential representation has gained wide acceptance. However, estimation and empirical assessment of this model has received little attention to date. The primary objective of this paper is to fill this gap. We use daily returns for the S&;P-500 and the NASDAQ indexes and individual stocks, in conjunction with maximum likelihood estimation (MLE) to fit the DEJD model. We utilize the BIC criterion to assess the performance of DEJD relative to log-normally distributed jump-diffusion (LJD) and the geometric brownian motion (GBM). We find that DEJD performs better than these alternatives for both indexes and individual stocks.     

An empirical comparison of continuous-time models of implied volatility indices

We explore the ability of alternative popular continuous-time diffusion and jump-diffusion processes to capture the dynamics of implied volatility indices over time. The performance of the various models is assessed under both econometric and financial metrics. To this end, data are employed from major European and American implied volatility indices and the rapidly growing CBOE volatility futures market. We find that the addition of jumps is necessary to capture the evolution of implied volatility indices under both metrics. Mean reversion is of second-order importance though. The results are consistent across the various metrics, markets, and construction methodologies.     

中国股市开、收盘波动性的比较研究

利用EGARCH模型,对2000年1月至2007年4月间沪深两市具有代表性的股票及指数的开收盘收益率的波动性进行实证分析,结果表明收益率序列有明显的ARCH效应,其波动性具有显著的非对称性的冲击的持续性;在样本期内,上交所的个股和指数未能观察到开盘波动性高于收盘波动性的现象,而深交所个股在2006年7月实施收盘集合竞价机制之后比较明显地观察到开盘波动性高于收盘波动性的现象。     

Has the Fed improved U.S. economic performance?

This paper finds that U.S. economic performance has not generally improved under the Federal Reserve, with the possible exception of the Great Moderation. We analyze the Fed and pre-Fed periods in terms of the rates and volatilities of inflation and real GDP growth. Comparing the pre-Fed periods to the post-World War II period and the Great Moderation, we find that real GDP growth has been lower under the Fed, while inflation has been higher. The volatilities of inflation and GDP growth have both declined under the Fed, but the reductions occurred mostly during the Great Moderation.