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.     

Finite sample properties of estimators for autoregressive moving average models

We analyze by simulation the properties of three estimators frequently used in the analysis of autoregressive moving average time series models for both nonseasonal and seasonal data. The estimators considered are exact maximum likelihood, exact least squares and conditional least squares. For samples of the size commonly found in economic applications, the estimators are compared in terms of bias, mean squared error, and predictive ability. The reliability of the usually calculated confidence intervals is assessed for the maximum likelihood estimator.     

When are adaptive expectations rational? A generalization

This note presents a simple generalization of the adaptive expectations mechanism in which the learning parameter is time variant. Expectations generated in this way minimize mean squared forecast errors for any linear state space model.     

Branding Decisions for Retailers’ Private Labels

Umbrella branding (UB) strategies for manufacturers’ products have received considerable attention in the literature. Not much is known about this strategy for private labels. Using a game-theoretic approach, we reassess the benefits of introducing a private label in a distinct category, and provide favorable conditions for the retailer to implement umbrella or individual branding for his private labels. We find that (1) UB leads to lower wholesale and retail prices for both national brands; (2) national brands’ manufacturers prefer individual branding over UB for private labels; and (3) the profitability of UB is not always guaranteed for the retailer.