Search results

The purpose of this paper is to explore the dark side of news community forums: the proliferation of opinion manipulation trolls. In particular, it explores the idea that a user who is called a troll by several people is likely to be one. It further demonstrates the utility of this idea for detecting accused and paid opinion manipulation trolls and their comments as well as for predicting the credibility of comments in news community forums.

The authors are aiming to build a classifier to distinguish trolls vs regular users. Unfortunately, it is not easy to get reliable training data. The authors solve this issue pragmatically: the authors assume that a user who is called a troll by several people is likely to be such, which are called accused trolls. Based on this assumption and on leaked reports about actual paid opinion manipulation trolls, the authors build a classifier to distinguish trolls vs regular users.

The authors compare the profiles of paid trolls vs accused trolls vs non-trolls, and show that a classifier trained to distinguish accused trolls from non-trolls does quite well also at telling apart paid trolls from non-trolls.

The troll detection works even for users with about 10 comments, but it achieves the best performance for users with a sizable number of comments in the forum, e.g. 100 or more. Yet, there is not such a limitation for troll comment detection.

The approach would help forum moderators in their work, by pointing them to the most suspicious users and comments. It would be also useful to investigative journalists who want to find paid opinion manipulation trolls.

The authors can offer a better experience to online users by filtering out opinion manipulation trolls and their comments.

The authors propose a novel approach for finding paid opinion manipulation trolls and their posts.

This paper shows that for a large class of single and multi‐factor term structure models, including the affine class, the market price of risk is directly related to the parameters of the stochastic processes of the underlying factors of the economy. It is shown that the market price of risk is proportional to the limit of the volatility of zero coupon bond returns. This means that the market price of risk is not entirely arbitrary. Not only it must be consistent with no arbitrage conditions, also it must be consistent with the parameters of stochastic processes of the factors that describe the economy. If the market price of risk is not correctly specified, then it could lead to profit opportunities of the type discussed in Backus et al (1996). Another consequence of our result is that in empirical tests of interest rate processes, the market price of risk should not be specified exogenously since its value is a function of the parameters of the model. We extend our result to forward processes. The market price of risk is shown to be a function of the volatility of the forward rate processes.

Previous studies show that crude oil is negatively correlated with stocks but has almost the same rate of return as stocks, and so adding crude oil into a portfolio with equities can provide significant diversification benefits for the portfolio. Given the diversification benefit of crude oil mixed with equities, we examine the value effect of crude oil derivatives transactions by oil and gas producers. Differing from traditional corporate risk management literature, this study examines corporate derivatives transactions from the shareholders' diversification perspective. The results show that crude oil derivatives transactions by oil and gas producers do impact value. If oil and gas producing companies stop shorting crude oil derivatives contracts, company stock prices increase significantly. In contrast, if oil and gas producing companies initiate short positions in crude oil derivatives contracts, stock prices tend to drop (still significant, but less so). Thus, hedging by producers is not necessarily good. Transaction limitation is shown to be one of the possible sources of the value effect of corporate derivatives transactions.