A comparison of diffusion approximations and actual limits in birth and death processes of noisy evolution

The stationary distribution of a birth and death process may not be approximated by a diffusion. The general situation is illustrated on the “musical chairs” model by Binmore et al. (1995). This model is shown to generate outcomes which are not captured by the concept of the ultralong run equilibrium selection introduced in Binmore et al. (1995).     

低碳知识的时空扩散与演变特征研究

基于维普中文科技期刊全文数据库中相关文献的时空分布变化,考量我国低碳知识经济扩散的形式、特征规律。结果发现：低碳知识在我国的时间扩散经历了接收、启动、加速、回落四个时期;低碳知识扩散中,政府是主导者,学者是领先者,企业是跟进者、居民是接受者;北京是我国低碳知识的扩散源,城市地位和文化科研实力是重要保障;低碳知识在我国的空间扩散既符合整体规律又表现出差异化。     

The adoption of Web 2.0 services: An empirical investigation

The paper investigates the factors associated with the intensity of use of three Web 2.0 services - video sharing, social networking and social bookmarking - by looking at the users' characteristics and at the technological features. It relies upon a theoretical framework that combines the diffusion of innovation model with the technology acceptance model. However, it goes beyond them by focusing not simply on the determinants of adoption, but on the determinants of the intensity of use, and by introducing variables related to the social influence. The empirical analysis is based upon a survey of 300 users of Web 2.0 services. We find that the compatibility with users' needs and behaviours plays an important role for the intensity of usage of both video sharing and social networking services, while the ease of use positively affects the intensity of usage of social networking services, but has a negative effect on the intensity of usage of video sharing services. Extrinsic job-related motivations are important drivers of the intensive usage of social bookmarking and social networking services, while sharing contents is relevant for video sharing and social networking services. Finally, individual characteristics such as age, education and IT endowment also play an important role.     

A choice-based multi-product diffusion model incorporating replacement demand

This study proposes an integrated forecasting model that incorporates both first purchase diffusion and replacement component of sales in predicting multi-product diffusion patterns. The model consists of a two-stage procedure that customers undertake during purchase occasions according to a diffusion process or replacement process, and at each occasion, they make purchase incidence decisions and product choices according to a choice model. By incorporating various exogenous factors in the choice model, the model can identify the impact of each factor on customers' purchase incidence decisions and choice decisions among various product sub-categories. This approach enables us to understand the overall process of customers' purchasing behavior and to separate total sales amount into sales to three consumer segments: first-time buyers, customers who repurchase the same product category and customers who change their previous product category. We applied the proposed model in the forecasting multi-product framework; forecasting sub-category level automobile sales and brand level mobile terminal sales in the South Korean market. The results of the empirical studies showed that incorporating the replacement components into the multi-product diffusion framework is useful not only in understanding the demand interaction among automobile categories and among mobile handset brands, but also in producing more accurate long-term sales forecasts compared to previous multi-product diffusion models.     

Different determinants at different times: B2B adoption of a radical innovation

This research aims to empirically determine which factors best explain business to business adoption of a radical, high-tech innovation early in the diffusion process. Early lifecycle data collection provides insights about the differences in determinants of adoption at different times in the product diffusion process. The results indicate that differences do exist between the determinants of early adoption, intent to adopt later, and unawareness of the innovation. The influencers of earliest adopters appear to be innovation-focused: the perceived benefits of the innovation as well as the strength of the producer network positively relate to early adoption; early adopters also tend to perceive the technology in the innovation as less different than previous technology than do those who intend to adopt later. The influence of a champion within the adopting firm, the ability of the firm to sense and respond to new technology, and the depth of technology knowledge within the adopting firm are significant influencers across multiple stages of diffusion, showing that firm-internal traits are particularly important influencers of adoption. Laggard firms are missing the critical firm traits that lead to information gathering and understanding of innovations. In addition to contributing to adoption research theory and methodology, this research has implications for innovation-marketing and innovation-adopting firms.     

A new approach to modelling sigmoidal curves

Growth and diffusion phenomena have become of great interest to investigators in many disciplines, such as Biology, Demography, Economy, Agriculture, etc. These processes are generally analyzed by means of growth curves. As, in nature, it is not possible for any variable to continue growing indefinitely, we can consider any growth process to have an upper limit or saturation level. Thus, should a model represent a growth phenomenon, it will be described by a sigmoidal or S-shaped curve. There are a wide variety of growth models in general and specific literature. Of these, the logistic model is without doubt one of the most studied in practice, as well as some modifications of it, including recent investigations directed to the decomposition of a growth curve into various logistic components [Technol. Forecast. Soc. Change 47 (1994) 89; Technol. Forecast. Soc. Change 61 (1999) 247.]. In all the cases above, the adopted approach includes fitting the trend curve to the data by means of a well-known estimation procedure, such as least squares. We suggest a somewhat different approach, which consists of expressing the model through its differential equation and searching for a functional specification for the variable representing growth rate. Two series have been chosen from the recent literature in order to illustrate the methodology presented.     

Undergraduate performance in accounting and business-based information technology

The pervasiveness of information systems (IS) in organizations mandates the need for high levels of IS skills. In recognition, professional bodies impose IS course requirements for accreditation. For both students and employers, performance in IS courses has become important. The tertiary entrance overall performance score accounted for 19.7 per cent of the variance in students' passing grades. Thereafter, proficiency in office automation software and programming accounted for 1.5 and 0.8 per cent of the variance, respectively. Students living in a stable, family home-based environment performed better and it is likely that this environment underpinned other factors affecting performance.     

A dynamic diffusion model for managing customer's expectation and satisfaction

The paper aims at answering the generic question on how suppliers make the suitable and well-timed decisions in diffusing new technology effectively to adopters. Three major attempts are made for the study: First, investigating the entire process of the adoption and diffusion of technology innovation with reasonably well-accepted models in each areas. Second, proposing an integrated model by concatenating in structured manner the three prominent models for the management of technology innovation such as diffusion model, adoption model, and customer satisfaction model. Third, exploring the dynamic mechanism underlying outward behaviors of the integrated model proposed in the study which depicts the causal relationships that influence technology adoption and diffusion behaviors. An exploration of the dynamic mechanism underlying outward behaviors of the integrated model is presented in the study by introducing the system dynamics simulation technique. These attempts made for the study and the results perhaps allow both researchers and practitioners to gain insight into the causal factors influencing customers' adoption decision making processes and thereby into the potential diffusion patterns resulting from those adoption processes.     

On capital injections and dividends with tax in a diffusion approximation

We consider a diffusion approximation to a risk process with dividends and capital injections. Tax has to be paid on dividends, but capital injections lead to an exemption from tax. That is, tax is only paid for the aggregate excess of dividends over the capital injections. The value of a strategy is the expected value of the discounted dividend payments after tax minus the discounted capital injections. We solve the problem and show that the optimal dividend strategy is a barrier strategy.