Inside the Crystal Ball: New Approaches to Predicting the Gasoline Price at the Pump

Appropriate real‐time forecasting models for the US retail price of gasoline yield substantial reductions in the mean‐squared prediction error (MSPE) at horizons up to 2 years as well as substantial increases in directional accuracy. Even greater MSPE reductions are possible by constructing a pooled forecast that assigns equal weight to five of the most successful forecasting models. Pooled forecasts have lower MSPE than the US Energy Information Administration gasoline price forecasts and the gasoline price expectations in the Michigan Survey of Consumers. We also show that as much as 39% of the decline in gas prices between June and December 2014 was predictable. Copyright © 2016 John Wiley & Sons, Ltd.     

The Effect of Behavioral Contagion and Tie-Strength on Calorie Intake in Food Courts

Major contributors to the obesity epidemic are societal and result from sedentary lifestyles and consumption of high-calorie diets. Previous studies suggest that food choice behavior is socially transmissible. Hence, knowledge of the impact of social influence on calorie intake is critical to improve the understanding about the outcomes of policies related to healthful diets. There is the need to analyze the influence of social networks on choosing food in a public place. Thus, we interviewed groups of food court patrons in an all-you-can-eat college dining hall. Results show individuals dining in a group with at least one obese group member are consuming more calories from high-calorie foods and fewer calories from low-calorie foods. Food-related interactions in a group influenced food consumption. Hence, dining with obese peers likely increases calorie intake.     

Career mentoring in context: A multilevel study on differentiated career mentoring and career mentoring climate

This study explores how supervisor career mentoring contributes to contemporary organizational career development, which strives to foster employees' promotability while strengthening their intention to stay. Specifically, we focus on the implications of career mentoring in team contexts. Applying a multilevel framework, we distinguish between individual‐level differentiated mentoring (i.e., an employee's mentoring perceptions as compared to those of other team members) and group‐level career mentoring climate (i.e., the average perception across all group members). In a workplace setting, we collected data from vocational job starters (N ranged from 230 to 290) and their company supervisors (N ranged from 56 to 68). We find that career mentoring climate positively relates to promotability, more so than differentiated career mentoring. Both career mentoring climate and differentiated career mentoring are positively related to the intention to stay. At the individual level, this relationship is mediated by job satisfaction. We discuss theoretical and practical implications of differentiated and group‐level mentoring.     

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Influence of organic and colloidal fouling on the removal of sulphamethoxazole by nanofiltration membranes.

This study investigated the effects of organic and colloidal fouling on the removal of a representative micropollutant sulphamethoxazole by two commercially available NF membranes. Alginate, bovine serum albumin and colloidal silica were selected as model foulants to simulate hydrophilic and hydrophobic organic fractions, and colloidal matter that are often found in treated effluent and surface water. Membrane fouling was related to the membrane and foulant characteristics and subsequently the separation behaviour of the micropollutant sulphamethoxazole under different solution pH. On the basis of these results, it was confirmed that membrane fouling is strongly dependent on both the foulant and membrane characteristics. The complex relationship among retention mechanisms, fouling mechanisms and the effects of fouling on retention was systematically delineated. Of the three model foulants selected for this study, colloidal fouling resulted in the most significant reduction in retention of sulphamethoxazole as well as inorganic salts, while flux decline as a result of colloidal fouling was quite moderate. Reduction in retention caused by fouling was attributed to a phenomenon known as cake-enhance concentration polarisation, which was a predominant mechanism of colloidal fouling. In addition, the reported results suggested that the effect of fouling on retention is also membrane pore size dependent.     

Accurate environmental bioindication in floodplains in spite of an extreme flood event

The ecological reaction of species on environmental factors can differ both, temporally and geographically. Therefore, bioindicator systems must be shown to remain accurate at different places and points of time. Extreme events pose challenges for testing this robustness, which has not yet been explored systematically. The unique opportunity of the extreme flooding of the river Elbe in August 2002 was used for such a test. The bioindicator system for mean groundwater depth during the vegetation period and annual duration of inundation in floodplains studied here was developed with data collected in 1999. Data from 2003 were used to analyse the dependence of the bioindication results on the humidity of the study plots and taxonomic group (plants, molluscs and carabid beetles). For the duration of inundation, the accuracy of bioindication in 2003 was similar to that in 1999, except for the medium‐humid and dry plots using molluscs as indicators. For groundwater depth, the accuracy of bioindication in 2003 was similar to that of the reference year except in the dry plots with significantly lower accuracy for all species groups. With a few exceptions, the bioindicator system is shown to be robust and to remain accurate in spite of an extreme flood event. In conclusion, the relevance of extreme events for the robustness of bioindicator systems differs between the indicated parameters and taxonomic groups. The results stress the need to take into account the limits of the working range and the occurrence of extreme events, when testing and applying bioindicator systems. Copyright © 2009 John Wiley & Sons, Ltd.     

Flexible estimation of price response functions using retail scanner data

Kalyanam and Shively [1998. Estimating irregular pricing effects: a stochastic spline regression approach. Journal of Marketing Research 35 (1), 16–29] and van Heerde et al. [2001. Semiparametric analysis to estimate the deal effect curve. Journal of Marketing Research 38 (2), 197–215] have demonstrated the usefulness of nonparametric regression to estimate pricing effects flexibly. The empirical results of these two studies, however, also revealed that nonparametric regression may suffer from too much flexibility leading to nonmonotonic shapes for price effects. In this paper, we show how the problem of nonmonotonicity can be dealt with without losing the power of flexible estimation techniques. We propose a semiparametric approach based on Bayesian P-splines with monotonicity constraints imposed on own- and cross-price effects. In an empirical application, we illustrate that flexible estimation of own- and cross-price effects can improve the predictive validity of a sales response model substantially, even when price response curves were constrained to show a monotonic shape, as suggested by economic theory. We also discuss the consequences from an unconstrained estimation of price effects.