Geographic concentration and vertical disintegration: Evidence from China

Existing theoretical literature predicts that geographic concentration encourages vertical disintegration of firms. Nevertheless, empirical evidence of this prediction is limited, especially in developing countries. Using data on manufacturing firms from China, this paper documents a positive correlation between geographic concentration and vertical disintegration. Additionally, this paper uses the instrumental variable approach to address the issue of endogeneity and finds that geographic concentration has a positive causal effect on vertical disintegration.     

Consumption norms,trickle-down and the video/microwave syndrome

A new method is presented for investigating empirically the presence or not of consumption norms in the ownership of durables amongst different socioeconomic groups (although the method is more generally applicable to any situation in which a number of characteristics, and not just durables, may be acquired in a specific sequence). In order to illustrate the method, some results are presented for the ownership of durables as sampled by the National Readership Survey for 1985 and 1990. As a further application of the method, particular attention is paid to the changing incidence of ownership of videos and microwaves. Both theoretically and empirically, the trickle-down model of consumer choice is critically assessed and found to be wanting.     

Hachemeister's Bayesian regression model revisited

Hachemeister's (1975) regression model is discussed from a number of viewpoints including credibility theory, Gauss-Markov theory and the Kalman filter. The last formulation facilitates recursive premium formulae including forecast errors. Recursive estimation of structural parameters is also briefly mentioned and an illustration involving a data set is presented. The paper basically serves to unify a number of recently developed ideas rather than present new results.     

微型晶体振荡器的研制

本文介绍的微型晶体振荡器有普通型、快速加热简易恒温型、多信号输出等三种类型晶振.其中快速加热简易恒温型在常温下工作时,频率—温度特性达10~(-7),在正温范围工作时,频—温特性达lO~(-6)/(0℃～80℃),多信号输出型目前已作出的每台晶振有1OMHz、5MHz、1MHz、500KHz、1OOKHz等五个频率的信号输出,其频率稳定度为10~(-5).晶振的振荡电路、放大电路、温控电路及分频电路,均以集成技术来实现,并与石英晶体谐振器—同用电阻焊密封于16×16×5.5(mm)~3的金属盒内,其重小于5克.