Analysis of a continuous-time proportional hazard model using discrete duration data

Many economic duration variables are often available only up to intervals, and not up to exact points. However, continuous time duration models are conceptually superior to discrete ones. Hence, in duration analyses, one faces a situation with discrete data and a continuous model. This paper discusses (i) the asymptotic bias of a conventional approximation procedure in which a discrete duration is treated as an exact observation; and (ii) the efficiency of a correct maximum likelihood estimator which appropriately accounts for the discrete nature of the data.     

在绵延中寻找美——柏格森美论述评

柏格森的美在绵延说是建立在其哲学本体论基础之上的。在他看来,只有绵延着的事物才是美的,所以美在绵延。美在绵延有四层含义:第一,任何绵延都是生命的绵延,所以美在绵延意味着美在生命;第二,绵延即无尽的生成,因此美在绵延又表明美在生成;第三,美在绵延也意味着美在统一;第四,因为把握了绵延的节拍能使人获得轻松感,所以美在绵延还表明美在轻松。美在绵延说是柏格森独特的美论,对于我们研究美很有参考价值。     

Analysis of some ruin-related quantities in a Markov-modulated risk model

In this paper, we study the joint Laplace transform and probability generating function of some random quantities that occur in each environment state by the time of ruin in a Markov-modulated risk process. These quantities include the duration spent in each state, the number of claims and the aggregate amount of claims that occurred in each state by the time of ruin. Explicit formulae for the joint transforms, given the initial surplus, and the initial and terminal environment states, are expressed in terms of a matrix version of the scale function. Moments and covariances of these ruin-related quantities are obtained and numerical illustrations are presented. The joint transform of the duration spent in each state, the number of claims, and the aggregate amount of claims that occurred in each state by the time the surplus attains a certain level are also investigated.     

Impact of support networks for breastfeeding: A multicentre study

Background

The rates of breastfeeding worldwide are slowly improving since 1996. Europe is still trailing behind the global breastfeeding incidence and prevalence rates. Thus, breastfeeding promotion, protection, prolongation and support have become an important challenge as breastfeeding sharply decreases in the first six months of life.

社会融合中的性别差异:流动人口工作搜寻时间的实证分析

文章以扩展传统的流动人口社会融合的静态研究视角,使用国家人口计生委2010年上半年流动人口动态监测调查数据,从男女农村流动人口工作搜寻时间的角度进一步比较农村流动人口融入流入地劳动力市场过程的性别差异及影响因素。文章采用持续时间模型,通过研究农村流动人口在流入地城市找工作所花费时间的影响因素,发现虽然在给定时间内,女性流动人口在流入地找到工作所花费的时间比男性要短,但女性找到高收入工作的概率要低于男性,而接受低收入工作的概率要大于男性,从而导致性别区隔的流动人口社会融入模式。     

小说学与“长时段”:论胡怀琛的中国小说史学

民国学者胡怀琛著有《中国小说研究》、《中国小说概论》、《中国小说的起源与演变》等普及型文学史著作,其研究理念与著述体例有别于鲁迅的《中国小说史略》。胡怀琛的中国小说史学以小说类型为经,以时代为纬,讲求小说学与小说史学的融合互渗,注重把握小说文体演变的内在逻辑与宏大结构。胡怀琛以现代意义的小说观为参照,重新整合经史子集中具有"小说"意味的文本,藉此重新发现中国的"小说",并重建各种历史文本与文类的关联性和有序性。胡怀琛将"长时段"的历史思维与解释方法运用于中国小说史研究,从"形"与"质"两方面勾勒出中国小说历史演化的基本轮廓。     

Spell incidence, spell duration and the measurement of unemployment

The proportion of the population out of work is an unsatisfactory measure of unemployment because it is indifferent to the way in which a given amount of unemployment time is distributed across the population. This paper offers a new way of measuring unemployment which takes account of both the frequency and duration of unemployment spells. The proposed unemployment index may be interpreted as the ‘welfare equivalent’ period of unemployment, and decomposes into the product of three components: a spell incidence factor, a duration factor, and the average unemployment rate.     

Additive Outlier Detection and Estimation for the Logarithmic Autoregressive Conditional Duration Model

This study investigates the influences of additive outliers on financial durations. An outlier test statistic and an outlier detection procedure are proposed to detect and estimate outlier effects for the logarithmic Autoregressive Conditional Duration (Log-ACD) model. The proposed test statistic has an exact sampling distribution and performs very well, in terms of size and power, in a series of Monte Carlo simulations. Furthermore, the test statistic is robust to several alternative distribution assumptions. An empirical application shows that parameter estimates without considering outliers tend to be biased.     

Measuring the Influence of Unemployment Insurance on Unemployment Experiences

This article investigates the comprehensive effects of unemployment insurance (UI) policies on the amount of time and unemployment that individuals report between jobs. The econometric model jointly determines the effects of UI on the lengths of nonemployment spells, the classification of these spells as unemployment, and the likelihood of collecting program benefits. The model carefully attempts to isolate variation in UI benefits attributable to differences in generosity across programs to avoid biases in estimating policy effects induced by other contaminating sources of benefit variation. Using data on men from the National Longitudinal Survey of Youth, the empirical results find (a) UI recipients typically experience longer spells between jobs, at least up to the exhaustion of UI benefits, and report substantially larger fractions of these spells as unemployment; (b) weekly benefit amounts exert no significant influence on the likelihood of UI recipiency, on the length of spells between jobs, or on the fraction of these spells classified as unemployment; and (c) increases in weeks of UI eligibility raise the likelihood of UI collection and lengthen the number of weeks of unemployment between jobs by inducing long spells to become longer and not by altering short-duration behavior.     

Unemployment duration and the measurement of unemployment

We propose a framework in which the welfare bases of various unemployment measures available in the literature can be analyzed and a decomposition of these measures can be made into aggregate unemployment and the concentration of its distribution. A set of axioms for an unemployment measure is then introduced, which relate to the sensitivity of an unemployment measure to the inequality in the distribution of the unemployment. An unemployment measure is derived on the basis of these axioms that captures the distributional considerations in the measurement of unemployment.