Existence of long memory in crude oil and petroleum products: Generalised Hurst exponent approach

This study examines the presence of long-run dependence in a variety of crude and refined energy spot markets during the 1986–2018 period using the time-varying generalised Hurst exponent. Our results indicate that the weak-form efficiency in energy spot markets is clearly time-varying, with USGC(U.S. Gulf Coast Conventional Gasoline) Diesel Fuel the most efficient and Propane the least. An important finding is that after the subprime crisis, the persistence of energy spot market products has increased. Overall, our finding highlights that the time-varying model is preferable to the time-constant one since the former can capture time-varying efficiency, which heavily depends on a country’s predominant economic and political conditions.     

Data preprocessing and quantile regression for probabilistic load forecasting in the GEFCom2017 final match

Team QUINKAN competed in the GEFCom2017 final match of hierarchical probabilistic load forecasting by adopting the quantile regression method using the R package quantreg. The weather stations were clustered into 11 groups, from which an optimal one was chosen for each load meter using the boosting method. The load meter records were cleaned and/or supplemented by various methods in order to secure robust quantile predictions. The variation in the regression formulas was kept as small as possible by introducing measures for suppressing prediction instability, although special formulas were employed for loading meters that were of an industrial nature. Several procedures were applied to help improve the accuracy, such as the smoothing of season transitions, coarse graining of the relative humidity, the use of load-oriented day-type definition, the averaging of weather data, and outlier removal.     

An evaluation of the Connected Nation broadband adoption program

Closing the digital divide and increasing broadband adoption within households and communities continues to be a target for government and nonprofit groups. While a large number of studies have examined policies and programs aimed at improving broadband infrastructure availability, little analysis to date has focused on evaluating efforts to increase adoption. One of the most well-known programs focused on adoption is Connected Nation, which partnered with 14 states to provide local curricula aimed at raising residential connection rates. This analysis uses a generalized difference-in-difference methodology to evaluate the effectiveness of the Connected Nation program in 5 states during 2012 and 2013. The results indicate that participation in the Connected Nation program had no significant impact on broadband adoption rates. This paper represents a rigorous evaluation of one of the most well-known adoption-oriented programs and emphasizes that measurable impacts of such efforts may not accrue over the short term.     

Foreign direct investment and economic growth: Is more financial development better?

We investigate the extent to which an increase in financial development affects the positive effect of foreign direct investment on economic growth. Although the financial sector is beneficial for economic growth, the effect of further financial development on growth is found to become insignificant. Using a dynamic panel threshold model on 62 middle- and high-income countries spanning the period 1987–2016, we re-examine the possible nonlinearity between finance, foreign direct investment, and growth. Consistent with the “vanishing effect” of financial development, we find significant evidence that foreign direct investment fosters growth in general, but the growth effect of foreign direct investment becomes negligible when the ratio of private sector credit to gross domestic product exceeds 95.6%. This finding is robust to different econometric methods, various subsamples and interaction analyses, and distinct financial development indicators.     

Time-varying inter-urban housing price spillovers in China: Causes and consequences

The spatial spillovers of housing prices across regions are well documented by a large body of previous studies. This paper tries to investigate the dynamic (time-varying) evolution of spatial interactions and their underlying driving factors intensively. Using a recently developed Generalized Autoregressive Score (GAS) model, this paper examines the time-varying spatial spillovers of housing prices in 70 major and median cities of China from 2006 to 2019. We find that the GAS model can well capture the impact of time-varying critical events of Chinese real estate market on the whole. However, different regions display heterogeneous variation patterns over time. Further investigation shows that inter-regional labor mobility and trades are two major channels, accounting for 1.25% and 2.58% of the monthly standard deviations of spatial spillover effects from one city to another, respectively. We also characterize and distinguish between three time-varying patterns of spatial spillovers within different regions of China. Our results shed lights on the understanding of spatial spillovers across regional real estate markets across different city network structures within China.     

An empirical analysis of multiple services and choices of consumer in the Swedish telecommunications market

Received analyses state that firms can use a multiple services offering strategy to retain customers and capture new customers. Factors that determine the multiple services strategy include product discount, service provider and customer characteristics. Consequently, this study addresses the fundamental question: what are the key determining factors that explain the probability that a consumer buys multiple services? A generalized Poisson regression model is employed to examine whether the product discount, service provider, socio-economic variables and geographical location impact consumer decisions. Data from a national survey in 2009 commissioned by Post-och Telestyrelsen, the Swedish telecommunications regulator, are analyzed. The results clearly show that the discount, service provider and income of the consumer affect the consumer׳s buying decision. A consumer who receives a discount or has a high income is more likely to buy multiple services or select more services from the current service provider into his basket than a consumer who does not receive discount or has lower income. Service providers, cable TV operators and telecommunications carriers can also lock-in their consumer and expand their market position from one particular service to another using bundling service. Thus, this may be the time for the telecommunications regulator to consider the market definition.     

Closed-form Bayesian inferences for the logit model via polynomial expansions

Articles in Marketing and choice literatures have demonstrated the need for incorporating person-level heterogeneity into behavioral models (e.g., logit models for multiple binary outcomes as studied here). However, the logit likelihood extended with a population distribution of heterogeneity doesn’t yield closed-form inferences, and therefore numerical integration techniques are relied upon (e.g., MCMC methods). We present here an alternative, closed-form Bayesian inferences for the logit model, which we obtain by approximating the logit likelihood via a polynomial expansion, and then positing a distribution of heterogeneity from a flexible family that is now conjugate and integrable. For problems where the response coefficients are independent, choosing the Gamma distribution leads to rapidly convergent closed-form expansions; if there are correlations among the coefficients one can still obtain rapidly convergent closed-form expansions by positing a distribution of heterogeneity from a Multivariate Gamma distribution. The solution then comes from the moment generating function of the Multivariate Gamma distribution or in general from the multivariate heterogeneity distribution assumed. Closed-form Bayesian inferences, derivatives (useful for elasticity calculations), population distribution parameter estimates (useful for summarization) and starting values (useful for complicated algorithms) are hence directly available. Two simulation studies demonstrate the efficacy of our approach. JEL Classification C6 · C8 · M3     

广义三棱柱地质模型的工程应用

采用广义三棱柱地质模型,实现工程地质的三维可视化,可以帮助工程人员迅速地掌握工程地质情况。     

Equitable preference relations on infinite utility streams

We propose generalized versions of strong equity and Pigou–Dalton transfer principle. We study the existence and the real-valued representation of social welfare relations satisfying these two generalized equity principles. Our results characterize the restrictions on one period utility domains for the equitable social welfare relations (i) to exist; and (ii) to admit real-valued representations.     

Generalized runs tests to detect randomness in hedge funds returns

The major contribution of this paper is to make use of generalized runs tests (Cho and White, 2011) to analyze the randomness, i.e. the lack of persistence, in both absolute and relative returns of hedge funds. We find that about 42% of the HFR universe exhibit iid absolute returns over the period spanning 2000 to 2012. These funds are mainly found in proportions within the Macro and Equity Hedge strategies. A similar result holds for relative returns. We also find that funds having non-iid returns often exhibit ARCH effects and structural breaks, with largest breaks located within financial crises. Also, only a small percentage displays persistence in their relative performance, 8.2% to 16.7% of the universe, mainly found in proportions within the Relative Value and Event-Driven strategies. The robustness of results is challenged by implementing the tests on a crisis-free period. We find similar results for absolute returns. For relative ones, differences appear across strategies and benchmarks, but still both ARCH and breaks are present. Our work contributes to the hedge fund literature in terms of methodology, portfolio allocation, and performance measurement.