马铃薯在中国传播的技术及社会经济分析

本文从生物、技术及社会经济的角度考证马铃薯在中国传播的过程，重点对传播条件和传播障碍进行阐述，分析了20世纪中国的社会变迁和科技进步对马铃薯传播的影响，并进一步讨论马铃薯扩种对我国粮食生产和社会生活的作用。     

Climate change, irrigation, and Israeli agriculture: Will warming be harmful?

This paper utilizes a Ricardian model to test the relationship between annual net revenues and climate across Israeli farms. The study finds that it is important to include the amount of irrigation water available to each farm in order to measure the response of farms to climate. With irrigation water omitted, the model predicts climate change is strictly beneficial. However, with water included, the model predicts that only modest climate changes are beneficial while drastic climate change in the long run will be harmful. Using the AOGCM Scenarios we show that farm net revenue is expected to increase. Although Israel has a relatively warm climate a mild increase in temperature is beneficial due to the ability to supply international markets with farm product early in the season.     

Research notes and communications corporate restructuring and strategic change: The effect on diversification strategy and R & D intensity

In the 1980s a number of large corporations restructured their diversified businesses through divestitures. It is hypothesized that restructuring activity focused on firms at intermediate levels of diversification (e.g., related-linked) which have a mixture of related and unrelated business units. Results confirm this hypothesis which explains that such mixed corporate strategies create organizational and control inefficiencies in managing both related and unrelated types of business units. Restructured firms were also found to move towards two types of different internal capital markets (related and unrelated). Most restructuring firms moved toward lower levels of diversification (e.g., related-constrained), although some moved toward higher levels of diversification (e.g., unrelated business). Also, this study finds restructuring firms that changed their corporate strategy by reducing diversified scope increased their R&D intensity. Firms that restructured and increased their diversified scope decreased R&D intensity. This result suggested a partial substitution between diversification and R&D activity.     

The influence of accountability on overconfidence and resistance to change: A research framework and experimental evidence

This paper presents a research framework and demonstrates how commitment to a particular course of action might lead to information search that is biased in favour of the chosen alternative. The framework also incorporates accountability as a strategy for mitigating overconfidence and resistance to change.An experiment was conducted to test the predictions of the proposed framework. Results of the experiment indicate that commitment to a particular cost allocation system leads to increased desirability of the chosen system and decreased desirability of the rejected alternative. The results also show that managers who are committed to a particular cost allocation system become too conservative and overconfident in their preferred system, which leads to high resistance to change. These effects, however, were attenuated by making the managers accountable for the negative consequences of their decisions.     

Use of minimum risk approach in the estimation of regression models with missing observations

This article considers a linear regression model with some missing observations on the response variable and presents two estimators of regression coefficients employing the approach of minimum risk estimation. Small disturbance asymptotic properties of these estimators along with the traditional unbiased estimator are analyzed and conditions, that are easy to check in practice, for the superiority of one estimator over the other are derived. Received May 2001     

Are Housing Price Cycles Driven by Irrational Expectations?

This paper investigates the extent to which condominium apartment prices are set in an efficient asset market. Unlike previous work that focuses on the time-series properties of measures of excess returns, the analysis is framed in terms of the changes in observable house prices over time. More precisely, the paper develops and applies a test of the joint null hypothesis of rational expectations, perfect markets, and no risk premium in the Vancouver condominium apartment market. The empirical results provide significant evidence against the joint null hypothesis. On average, ex post house price changes move in a direction opposite to their rational expectation. This approach offers a methodological advantage over the standard efficiency literature and is shown to provide a more powerful test of market efficiency than conventional return regressions. Another contribution of the paper is to characterize the time-series properties of deviations of condominium prices from those predicted by the risk-neutral rational expectations model, using cointegration and random coefficients techniques. Deviations in house price changes from their (risk-neutral) rational expectations are time varying, stationary, and related to the stage of the real estate price cycle.     

Learning across the life cycle: Experimentation and performance among the hollywood studio heads

Guided by notions from the literature on organizational learning, this paper investigates how product line experimentation and organizational performance change across the careers of top managers. Its subjects are the studio heads who ran all the major Hollywood film studios from 1936 to 1965. The study found first, that product line experimentation declines over the course of executive tenures; second, that there is an inverse U‐shaped relationship between top executive tenure and an organization's financial performance; and third, that product line experimentation is more likely to benefit financial performance late in top executives' tenures. These findings are consistent with a three‐stage ‘executive life cycle’. During the early years of their tenures, top managers experiment intensively with their product lines to learn about their business; later on their accumulated knowledge allows them to reduce experimentation and increase performance; finally, in their last years, executives reduce experimentation still further, and performance declines. Copyright © 2001 John Wiley & Sons, Ltd.     

Research on Generation Mechanism of Technical Innovation

Technical advancement includes technology generation, diffusion and aggregation. This paper focuses on researching the mechanism of technology generation from the viewpoint of technology cycle, and the source spring of the generation of the innovation based on technology is scientific discovery. The technical perfection and secondary innovation are determined by the pulling force of demand, unbalanced inducement mechanism and profit. Standardized innovation is the sign of technology mature stage, the limit in demand and supply of technology drives the technical innovation into lag phase.     

Strategic groups as reference groups: Theory,modeling and empirical examination of industry and competitive strategy

Previous studies on strategic groups have mainly focused on their static characteristics in order to test the theory of strategic groups and intraindustry performance differences (Porter, 1979; Cool and Schendel, 1988; Fiegenbaum and Thomas, 1990). In contrast, this study takes a longitudinal, dynamic perspective and describes the forces driving strategic group membership and structural evolution. It proposes that a strategic group acts as a reference point for group members in formulating competitive strategy. A partial adjustment model of strategic mobility is then developed which incorporates the idea of a strategic group as a reference group. It models strategic change in an industry both within and across strategic groups. The model is tested in the context of an in-depth industry analysis of the more significant firms in the insurance industry over the 1970-84 time period. The results suggest that strategic groups act as reference points for firm strategies and that predictions of future firm strategies and industry/group structures may also be successfully derived.