The Dynamics of Self-Esteem and Physical Self: Between Preservation and Adaptation

The aim of this study was to model and characterize the psychologicalprocesses that underlie the dynamics of global self-esteem and physicalself over time. Twice a day for 228 consecutive days, seven participantscompleted a short inventory (PSI-6, Ninot et al., 2001) measuring sixsubjective dimensions: global self-esteem, physical self-worth, physicalcondition, sport competence, physical strength, and attractive body.Each series was modeled by means of ARIMA procedures. The resultsshowed that a simple moving average model provided a satisfactoryaccount for the dynamics of all series. This model suggests that acombination of two opposite processes underlies the dynamics ofself-concept: preservation, which tends to restore the previousvalue after a disturbance, and adaptation, which tends to inflectthe series in the direction of the perturbation.     

Using diffusion models to forecast market size in emerging markets with applications to the Chinese car market

Marketing managers have to forecast the market size and this forecast guides strategic decisions whether to continue exporting, open new factories or expand existing production operations. Forecasting sales and the market size is a challenging task; even more so in emerging markets where data is limited and the market demand is changeable. This research proposes a novel approach that applies diffusion models using car ownership data to forecast car sales. Car ownership data may be easier to access than sales data in emerging markets but marketing managers are more interested in the sales forecast. Researchers propose using diffusion models to forecast the adoption of new products or products which are new to consumers in a market. This research demonstrates that marketing managers can use diffusion models to predict car sales in China where cars are new products to most consumers in this market. Since the majority of car buyers in China are first time buyers, car manufacturers and retailers must also forecast when the market composition will change. This effectively means predicting when first time car buying will start to slow down and repeat/replacement purchase or second hand car purchase will become more important. To forecast both sales and market composition change, marketing managers must choose a robust model. Managers want insights from models that have been tested robustly especially in less stable market conditions. In this context, this study illustrates the value of using a rolling forecast instead of a fixed horizon approach when comparing and choosing which model to use to forecast both sales and market composition change for the Chinese car market.     

Vertical Disintegration: A Dynamic Markovian Approach

In a model where a monopolistic downstream firm (assembler) negotiates simultaneously with each of its intermediate‐input suppliers the prices of the complementary components which enter its product, we analyze the process by which the assembler separates from its suppliers as a Markov Perfect equilibrium. Due to a negative strategic effect (the prices and profits of independent suppliers decrease when their number increases), the assembler’s marginal return from keeping an upstream subsidiary is lower than the market value of an independent supplier. Separation is immediate when the downstream firm’s initial number of upstream subsidiaries is below a critical level. It is progressive in the reverse case and eventually leads to a mixed strategy whereby the assembler keeps all the remaining subsidiaries with some probability, and sells all them off in one go with the complementary probability.     

The endo–exo problem in high frequency financial price fluctuations and rejecting criticality

The endo–exo problem lies at the heart of statistical identification in many fields of science, and is often plagued by spurious strong-and-long memory due to improper treatment of trends, shocks and shifts in the data. A class of models that has shown to be useful in discerning exogenous and endogenous activity is the Hawkes process. This class of point processes has enjoyed great recent popularity and rapid development within the quantitative finance literature, with particular focus on the study of market microstructure and high frequency price fluctuations. We show that there are important lessons from older fields like time series and econometrics that should also be applied in financial point process modelling. In particular, we emphasize the importance of appropriately treating trends and shocks for the identification of the strength and length of memory in the system. We exploit the powerful Expectation Maximization algorithm and objective statistical criteria (BIC) to select the flexibility of the deterministic background intensity. With these methods, we strongly reject the hypothesis that the considered financial markets are critical at univariate and bivariate microstructural levels.     

Transportation conditions and access to services in a context of urban sprawl and deregulation. The case of Dar es Salaam

Major deficiencies in urbanisation and transportation systems are reinforcing patterns of social and urban segregation in Dar es Salaam, Tanzania's largest city. Analysis of the 1993 Human Resources Development Survey shows that there are numerous obstacles to the daily travel of the city's inhabitants, notably the poor. These barriers weigh heavily on schedules, complicate access to services ever further, limit the use of urban space, and place considerable pressure on household budgets. Consequently, the poorest individuals tend to retreat into their neighbourhood where the low-quality urban facilities are unable to assist in the development of human and social capital and economic opportunities, the alleviation of poverty or the prevention of social exclusion.     

Consumer decision making,E-commerce and perceived risks

This article studies how adoption and usage behaviour of the Internet and online shopping, respectively influence the preference to use electronic commerce to purchase different types of products. We empirically model the preference for electronic commerce when consumers have to buy different types of products and thus face different types of risks (Cox and Rich, 1964 Cox, D and Rich, S. 1964. Perceived risk and consumer decision making-the case of telephone survey. Journal of Marketing Research, 1: 32–9. [Crossref], [Web of Science ®] , [Google Scholar]). Unlike previous research, we find that consumers who have previously shopped online, display stronger preferences to buy products on the Internet irrespective of the perceived level of product-specific risks of online shopping. This article provides an interesting and novel insight into how both adoption and usage of electronic commerce impact on the attitude and risk perception of buying less predictable (more risky) products on the Internet.