Social question and answer (Q&A) communities or websites, such as Quora, StackOverflow, become popular from the last decade. They provide collected answers in a crowdsourcing way by encouraging the interactive between users. The ranking of answers in such Q&A websites depends on many factors, such as received upvotes, downvotes, publishing time, and so on. When there exist malicious users, they can manipulate the ranking of answers by launching voting spamming attacks. In this article, we propose a metric, diversity of visibility, to characterize the balance between rankings of answers with conflicting opinions and propose a time-diversitybased voting scheme to reach a high diversity of visibility, so as to minimize the impact of voting spamming attacks. We evaluate the proposed metric and voting scheme in the case study of a Chinese Q&A website, Zhihu, and show that the proposed voting scheme consistently shows a good balance of answers with conflicting opinions in both actual scenarios and synthetic scenarios.
- Question and answer community
- Ranking algorithm
- Social networks