Applying Time Series Decomposition to Construct Index-Tracking Portfolio

This study proposes a new method for creating an index-tracking portfolio using time series decomposition. First, we construct index-tracking portfolios of stocks chosen because their price movements mimic that of the Dow-Jones Industrial Average. Our method utilizes similarities of constituent stocks to the benchmark that are assessed by distances of time series trends derived from decomposing original series. Although the portfolios chosen by our method reasonably tracked the performance of the benchmark, they did not surpass the clustering approach discussed in earlier studies. Therefore, we examined what causes tracking error and found that two causes for deficiencies in our similarity-based method, which are unintended irregular movements of holding stocks and highly correlated relationships within stocks in the portfolio. To overcome them and to improve tracking performance, we propose a similarity-balanced approach that is another index-tracking method with alternate use of similarity. Doing so improved the tracking performance by avoiding the problem of high correlation among the stocks chosen under the initial method.     

Spatial Cournot competition and economic welfare: a note

We investigated welfare implications in location-quantity models in a symmetric linear city. We found that when firms are not agglomerated in equilibrium, increasing the distance between firms raises (reduces) producer surplus and social welfare (consumer surplus). Moreover, central agglomeration is always optimal for consumers among symmetric locations, but not necessarily for producers. Central agglomeration can be inefficient even if it is the unique equilibrium outcome. In short, the firms are more likely to agglomerate or locate closer than what welfare maximizers would dictate, whereas they locate farther apart than what consumer surplus maximizers would recommend.     

Spurious regressions in technical trading

This paper investigates the spurious effect in forecasting asset returns when signals from technical trading rules are used as predictors. Against economic intuition, the simulation result shows that, even if past information has no predictive power, buy or sell signals based on the difference between the short-period and long-period moving averages of past asset prices can be statistically significant when the forecast horizon is relatively long. The theoretical analysis reveals that both ‘momentum’ and ‘contrarian’ strategies can be falsely supported, while the probability of obtaining each result depends on the type of the test statistics employed.     

Effects of direct payments on rice income variability in Japan*

The effects of direct payments on rice income variability in Japan are analysed based on a balanced panel dataset of Japanese rice farms for 2012–2016. Firstly, the contribution of income components to rice income variability and the effects of a direct payment reduction are discussed by applying variance decomposition. Secondly, robust regression techniques are used to measure the correlation between direct payments and rice income variability. The originality of this paper is that it disaggregates the effects of payments using a regression analysis of the effects of direct payments on income variability for Japan. This contrasts with the existing literature on this topic, which has largely focused on European Union countries. This paper discusses to what degree the reduction in direct payments increases income variability. The results reveal that direct payments decrease Japanese rice income variability. Indeed, after controlling for various farm characteristics, we find a negative relationship between the amount of direct payments linked to rice production and rice income variability. Finally, the results suggest that reducing direct payments when the rice price is falling would increase rice income variability.