A bivariate distribution with Lomax and geometric margins

We develop a stochastic model describing the joint distribution of $(X,N)$, where $N$ has a geometric distribution while $X$ is the sum of $N$ dependent, heavy-tail Pareto components. Models of this form arise in many applications, ranging from hydro-climatology to finance and insurance. We present fundamental properties of this vector, including marginal and conditional distributions, moments, representations, and parameter estimation. We also include an example from finance, illustrating modeling potential of this new bivariate distribution.     

期权“净购买压力”的隐含信息

使用50ETF期权的高频数据，研究“净购买压力”指标对指数方向性和波动性变化的预测能力，并比较不同加总方法、看涨看跌、不同在值程度的期权以及非对称的“净购买压力”指标隐含信息的差异性.本文发现，50ETF期权“净购买压力”指标隐含着标的指数方向性和波动性的变化信息.在预测指数变化方向时，Delta加总的“净购买压力”隐含的信息已包含在简单加总的指标之中，看涨、看跌期权以及不同在值程度的期权在信息含量上存在差异性.在预测指数波动性时，使用简单加总和使用Gamma、Vega加总的“净购买压力”指标均隐含着未来市场的波动率信息，平值和虚值期权的“净购买压力”指标对波动率具有更强的预测能力.同时，“净购买压力”的隐含信息存在非对称特征.     

Optimal designs for response functions with a downturn

In many toxicological assays, interactions between primary and secondary effects may cause a downturn in mean responses at high doses. In this situation, the typical monotonicity assumption is invalid and may be quite misleading. Prior literature addresses the analysis of response functions with a downturn, but so far as we know, this paper initiates the study of experimental design for this situation. A growth model is combined with a death model to allow for the downturn in mean doses. Several different objective functions are studied. When the number of treatments equals the number of parameters, Fisher information is found to be independent of the model of the treatment means and on the magnitudes of the treatments. In general, A- and D_A-optimal weights for estimating adjacent mean differences are found analytically for a simple model and numerically for a biologically motivated model. Results on c-optimality are also obtained for estimating the peak dose and the EC₅₀ (the treatment with response half way between the control and the peak response on the increasing portion of the response function). Finally, when interest lies only in the increasing portion of the response function, we propose composite D-optimal designs.     

20世纪50年代新诗对后期延安诗歌的“继承”

20世纪50年代新诗在“继承”后期延安诗歌创作资源过程中,呈现的内容是多样化的.除体制、队伍、生产与接受之外,风格与形式的相应延续,也在很大程度上影响到了50年代新诗的面貌.但无论就时代还是区域范围的差异,“继承”只是一个相对的概念.50年代新诗在自身发展过程中一直有自己的潜在内容,而其被“简约”的过程,正是历史延续过程中的复杂化部分.     

Towards expenditure rules and fiscal sanity in the euro area

The study demonstrates the key role of expenditure policies in explaining fiscal developments during EMU in the euro area, its three largest members and four “macro-imbalances” countries. It compares actual primary expenditure trends with those that would have prevailed if countries had followed neutral policies based on expenditure rules since the start of EMU. Moreover, the implications for debt trends are calculated. Results show that all sample countries except Germany applied expansionary expenditure policies already before the crisis. Consequently, expenditure and debt paths were much higher compared to a counterfactual neutral expenditure stance. Rule-based expenditure policies could have led to much safer fiscal positions much more in line with the EU's Stability and Growth Pact. An empirical analysis of the determinants of countries’ expenditure stance confirms the need for stronger fiscal rules and institutions in the euro area.     

Allometric Scaling: Analysis of LD50 Data

The need to identify toxicologically equivalent doses across different species is a major issue in toxicology and risk assessment. In this article, we investigate interspecies scaling based on the allometric equation applied to the single, oral LD ₅₀ data previously analyzed by Rhomberg and Wolff.⁽ 1 ⁾ We focus on the statistical approach, namely, regression analysis of the mentioned data. In contrast to Rhomberg and Wolff's analysis of species pairs, we perform an overall analysis based on the whole data set. From our study it follows that if one assumes one single scaling rule for all species and substances in the data set, then β= 1 is the most natural choice among a set of candidates known in the literature. In fact, we obtain quite narrow confidence intervals for this parameter. However, the estimate of the variance in the model is relatively high, resulting in rather wide prediction intervals.     

一种混合建模方法及其在ETF期权定价中的应用

科学合理的交易型开放式指数基金（ETF）期权定价有利于充分发挥其风险对冲功能,也是一个需要准确掌握市场规律并兼顾经济学意义的复杂建模过程。本文提出了一种新的混合建模方法,将嵌套长短时记忆神经网络模型（NLSTM）与Heston模型结合,实现ETF期权定价偏差的动态修正,并基于华夏上证50ETF、嘉实沪深300ETF和华泰柏瑞沪深300ETF的高频期权数据,实验验证了所提方法的有效性。研究结果表明,不同类型ETF期权价格的波动特征差异显著,无论是基于BS定价模型还是Heston定价模型都难以准确刻画ETF期权价格的复杂变化规律。通过将NLSTM神经网络模型与Heston模型结合,能够有效地捕捉不同类型ETF期权的动态变化规律,从而提升ETF期权定价的准确性。     

Optimality and bias of some interpolation and extrapolation designs

We consider interpolation and extrapolation designs with controlled bias. A consistent estimate of an upper bound of the bias is presented. The estimate of some extrapolated value is obtained in a two-stage procedure. The first one provides an estimate of some interpolated value. The second one uses a Taylor expansion around this point. This procedure yields a new type of designs. We discuss their optimality properties with respect to the variance and the bias.     

上证50股票价值的综合评价

采用主成分分析法对上证50的全部50家上市公司的股票价值进行综合评价。首先从这50家上市公司2005年度的财务报表数据中选取十一个重要指标作为基础,利用主成分分析法加以处理,合并为三个主成分,代入综合评价函数得到这50家上市公司股票的综合得分和综合排名;再对标准化的各因素指标的权重作进一步的讨论,最终得出这50家上市公司股票的综合排名。     

融资融券能促进标的证券的定价效率吗?——基于上证50ETF的实证研究

通过分析ETF作为融资融券标的前后折溢价率水平变化及其影响因素,发现融资融券推出和交易费用减免都显著提高了ETF的定价效率。具体而言,融资融券推出与交易费用减免都是通过影响ETF的套利成本来提高其定价效率的。交易费用减免一方面直接降低了套利显性成本,另一方面通过提高市场流动性降低了套利隐形成本;而融资融券推出为ETF交易提供了额外的套利渠道,降低了市场非流动性对原有的跨市场套利的影响,从而提高其定价效率。