1,722,318 research outputs found
Tang ren chuang zuo xiao shuo xuan.
No full text上海中央書店[編] ; [儲菊人校訂].Shanghai zhong yang shu dian [bian] ; [Chu Juren jiao ding]
Loss of disc height in instrumented posterior lumbar interbody fusion using keystone bone grafts
No full textA SEMIPARAMETRIC INFERENCE TO REGRESSION ANALYSIS WITH MISSING COVARIATES IN SURVEY DATA
No full textParameter estimation in parametric regression models with missing covariates is considered under a survey sampling setup. Under missingness at random, a semiparametric maximum likelihood approach is proposed which requires no parametric specification of the marginal covariate distribution. By drawing from the von Mises calculus and V-Statistics theory, we obtain an asymptotic linear representation of the semiparametric maximum likelihood estimator (SMLE) of the regression parameters, which allows for a consistent estimator of asymptotic variance. An EM algorithm for computation is then developed to implement the proposed method using fractional imputation. Simulation results suggest that the SMLE method is robust, whereas the fully parametric method is subject to severe bias under model misspecification. A rangeland study from the National Resources Inventory (NRI) is used to illustrate the practical use of the proposed methodology.
The role of store brand positioning for appropriating supply chain profit under shelf space allocation
No full textWe consider a retailer's decision of developing a store brand (SB) version of a national brand (NB) and the role that its positioning strategy plays in appropriating the supply chain profit. Since the business of the retailer can be regarded as selling to NB manufacturers the shelf space at its disposal, we formulate a game-theoretical model of a single-retailer, single-manufacturer supply chain, where the retailer can decide whether to launch its own SB product and sells scarce shelf-space to a competing NB in a consumer good category. As a result, the most likely equilibrium outcome is that the available selling amount of each brand is constrained by the shelf-space available for its products and both brands coexist in the category. In this paper, we conceptualize the SB positioning that involves both product quality and product features. Our analysis shows that when the NB cross-price effect is not too large, the retailer should position its SB's quality closer to the NB, more emphasize its SB's differences in features facing a weaker NB, and less emphasize its SB's differences in features facing a stronger NB. Our results stress the importance of SB positioning under the shelf-space allocation, in order to maximize the retailer's value appropriation across the supply chain. © 2013 Elsevier B.V. All rights reserved
A note on multiple imputation under complex sampling
No full textMultiple imputation is popular for handling item nonresponse in survey sampling. Current multiple imputation techniques with complex survey data assume that the sampling design is ignorable. In this paper, we propose a new multiple imputation procedure for parametric inference without this assumption. Instead of using the sample-data likelihood, we use the sampling distribution of the pseudo maximum likelihood estimator to derive the posterior distribution of the parameters. The asymptotic properties of the proposed method are investigated. A simulation study confirms that the new procedure provides unbiased point estimation and valid confidence intervals with correct coverage properties whether or not the sampling design is ignorable.
Growing artificial entrepreneurs
No full textPurposeThe aim of this paper is to offer agent‐based modelling (ABM) as an alternative approach to advance research in entrepreneurship. It argues that ABM allows entrepreneurship researchers (i.e. the designers) to find better ways in generating entrepreneurial outcomes by understanding alternative histories and examining a plausible future.Design/methodology/approachThis paper begins with an overview of ABM, and discusses the shared conceptual foundations of entrepreneurship and ABM as the motives for the adoption of ABM as an appropriate methodology to study entrepreneurship. It offers a roadmap in using ABM approach for entrepreneurship research and illustrates this using a contemporary research question in entrepreneurship: the study of success/failure in business venturing.FindingsThis paper suggests the shared foundations between ABM and entrepreneurship as the basis for bringing the methodology and research domain closer. It offers a roadmap for advancing entrepreneurship research using agent‐based simulation approach and explains the contribution of ABM to further advance entrepreneurship research.Originality/valueThis paper addresses the methodological gap in entrepreneurship research and develops the argument for a wider adoption of ABM simulation approach to study entrepreneurship. It bridges the gap by examining the possibility of formalizing entrepreneurship processes by grounding an agent‐based model on empirical facts and generally‐accepted foundations of entrepreneurship. It offers a contribution to the literature by showing that ABM is a useful and appropriate methodological approach for entrepreneurship research in addition to the conventional variance and process approach.</jats:sec
Managing Disruptive Innovation: Entrepreneurial strategies and tournaments for corporate longevity
No full textExtant research on disruptive innovation has implicitly incorporated entrepreneurship as the underlying driver of the disruptive phenomenon. This article integrates recent developments from entrepreneurship and innovation research streams to better understand the conditions and causal mechanisms that influence disruptive innovation. Drawing on effectuation, evolutionary entrepreneurship, lead-users, collective intelligence and opportunity tournament literature, a theoretical framework is developed that explains disruptive innovation as a co-evolutionary entrepreneurial process at the firm, product, and customer level. The framework offers a set of testable propositions to advance theory and practice in the field. The authors suggest avenues for future research and conclude with entrepreneurial strategies to help general managers create and cope with disruptive innovation.</jats:p
The timing of capacity investment with lead times: when do firms act in unison?
No full textWe study competitive capacity investment for the emergence of a new market. Firms may invest either in capacity leading demand or in capacity lagging demand at different costs. We show how the lead time and other operational factors including volume flexibility, existing capacity, and demand uncertainty impact equilibrium outcomes. Our results indicate that a type of bandwagon behavior is the most likely equilibrium outcome: if both firms are going to invest, then they are most likely to act in unison. Contrary to much received wisdom, we show that leader–follower behavior is very uncommon in equilibrium where firms do not have volume flexibility, and will not occur at all if lead times are sufficiently short. On the other hand, if there is volume flexibility in production, then the likelihood of this sequential investment behavior increases. Our findings underscore the importance of operational characteristics in determining the competitive dynamics of capacity investment timing
Anticipated responses: The positive side of elicited reactions to competitive action
No full textThis study advances the action-oriented perspective on strategy dynamics. Strategy research suggests that a firm’s profit will decrease when facing rival responses, yet anecdotal evidence indicates that countermoves may enhance its performance. What is the interaction effect of simultaneous negative- and positive-side competitive responses on organisational performance? We propose that the answer depends not only on the actor’s characteristics but also the action’s characteristics. Grounded in empirical facts, our formal model of competitive dynamics examines the possibility of anticipated responses that are deliberately elicited by the attacking firm. We show that against attentive rivals, a firm with high attention and low aggressiveness can utilise visible actions to achieve its strategic intention and deployment. Our study offers significant implications for theory and practice
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