中国健康保险市场规模实证分析

健康保险是中国医疗保障制度的重要组成部分,健康保险市场规模的扩张使得保险在中国能够更好地发挥经济补偿功能、资金融通功能与社会管理功能。本文借鉴前人的研究成果,利用国内生产总值、社会与个人卫生支出以及健康险保费收入的历年数据,构建误差修正模型(ECM),并寻找社会与个人卫生支出同健康险保费收入之间的数量关系,进而预测分析国内健康保险市场的发展规模、空间及方向。     

A review and comparison of medical expenditures models: two neural networks versus two‐part models

This paper compares the two‐part model (TPM) that distinguishes between users and non‐users of health care, with two neural networks (TNN) that distinguish users by frequency. In the model comparisons using data from the National Health Research Institute (NHRI) in Taiwan, we find strong evidence in favor of the neural networks approach. This paper shows that the individuals in the self‐organizing map (SOM) network clusters can be described as several different forms of frequency distributions. The integration model of SOM and back propagation network (BPN) proposed by this paper not only permits policymakers to easily include more risk adjusters besides the demographics in the traditional capitation formula through the adaptation and calculation power of neural networks, but also reduces the incentives for cream skimming by decreasing estimation biases.     

Binomial Option Pricing Biases and Inconsistent Implied Volatilities

We evaluate the binomial option pricing methodology (OPM) by examining simulated portfolio strategies. A key aspect of our study involves sampling from the empirical distribution of observed equity returns. Using a Monte Carlo simulation, we generate equity prices under known volatility and return parameters. We price American–style put options on the equity and evaluate the risk–adjusted performance of various strategies that require writing put options with different maturities and moneyness characteristics. The performance of these strategies is compared to an alternative strategy of investing in the underlying equity. The relative performance of the strategies allows us to identify biases in the binomial OPM leading to the well–known volatility smile . By adjusting option prices so as to rule out dominated option strategies in a mean–variance context, we are able to reduce the pricing errors of the OPM with respect to option prices obtained from the LIFFE. Our results suggest that a simple recalibration of inputs may improve binomial OPM performance.     

Empirical tests of real estate market efficiency

Recent empirical research using real estate data has supported the weak and semi-strong forms of the efficient markets hypothesis. Previous studies have not included an estimate of expected appreciation into the tests of market efficiency, thus raising a question about the reliability of the results. We first use a market model to test for market efficiency with results similar to those reported by others. We next use a dynamic multiple indicator, multiple cause (DYMIMIC) model, which extracts a vector of expected appreciation from the price data, to test market efficiency. This approach produces superior results and a stronger conclusion about the efficiency of housing markets. The results indicate limited adjustment delays which can be explained by the existence of high transactions and search costs.     

Subordinated Market Index Models: A Comparison

The paper compares various processes subordinated to the Wiener process tomodel the leptokurtic characteristics of index returns. Empirical analysisis performed on the Dow Jones and Nikkei 225 indexes. A good model to capturethe typical tail behaviour of these indexes turns out to be a long Studentt distributed one.     

Pricing Bonds and Bond Options with Default Risk

The pricing of bonds and bond options with default risk is analysed in the general equilibrium model of Cox, Ingersoll, and Ross (1985). This model is extended by means of an additional parameter in order to deal with financial and credit risk simultaneously. The estimation of such a parameter, which can be considered as the market equivalent of an agencies' bond rating, allows to extract from current quotes the market perceptions of firm's credit risk. The general pricing model for defaultable zero-coupon bond is first derived in a simple discrete-time setting and then in continuous-time. The availability of an integrated model allows for the pricing of default-free options written on defaultable bonds and of vulnerable options written either on default-free bonds or defaultable bonds. A comparison between our results and those given by Jarrow and Turnbull (1995) is also presented.     

Transfers in Spanish State Retirement Pensions

A central issue in the recent reforms of state pensions in Spain has been to increase the proportionality between contributions and benefits along actuarially fair lines. The aim of this paper is to quantify the transfer component of social security retirement pensions, with transfer being understood as the difference between the pension effectively received and that which would be received under a system of actuarial fairness. The analysis is placed within a life-cycle framework, with particular reference to the distributive effects by income level. The results show that, in the past, there was a marked bias in favour of the objective of intergenerational and intragenerational redistribution, to the detriment of the objective of income insurance. This paper examines the factors that determine the final value of the transfer component within the entire Spanish pensions system.     

Closed-form valuation of American call options on stocks paying multiple dividends

An American call option on a stock paying a single known dividend can be valued using the Roll–Geske–Whaley formula. This paper extends the Roll–Geske–Whaley model to the n dividends case by using the generalized n-fold compound option model. In this way this paper offers a closed-form solution for American options on stocks paying n known discrete dividends. Moreover, the model also offers the critical values of the early exercise boundaries at each ex-dividend date instant, making it easy to define an early exercise strategy. Numerical examples are included to illustrate this approach.     

Time Inhomogeneous Multiple Volatility Modeling

Price variations at speculative markets exhibit positive autocorrelationand cross correlation. Due to large parameter spaces necessaryfor joint modeling of variances and covariances, multivariateparametric volatility models become easily intractable in practice.We propose an adaptive procedure that identifies periods ofsecond-order homogeneity for each moment in time. To overcomethe high dimensionality of the problem we transform the multivariateseries into a set of univariate processes. We discuss thoroughlythe implementation of the adaptive technique. Theoretical andMonte Carlo results are given. We provide two applications ofthe new method. For a bivariate exchange rate series we comparethe multivariate GARCH approach with our method and find thelatter to be more in line with the underlying assumption ofindependently distributed innovations. Analyzing a 23-dimensionalvector of asset returns we underscore the case for adaptivemodeling in high-dimensional systems.     

Impact of Divergent Consumer Confidence on Option Prices

This paper investigates the impact of divergent consumer confidence on option prices. To model this, we assume that consumers disagree on the expected growth rate of aggregate consumption. With other conditions unchanged in the discrete-time Black–Scholes option-pricing model, we show that the representative consumer will have declining relative risk aversion instead of the assumed constant relative risk aversion. In this case all options will be underpriced by the Black–Scholes model under the assumption of bivariate lognormality. This revised version was published online in June 2006 with corrections to the Cover Date.