A key observation in coalition formation is that bargainers with most resources are often excluded from coalitions: the Strength-is-Weakness effect. Previous studies have suffered from low sample sizes and lack of (appropriate) incentives and have rarely focused on underlying processes. To address these issues, we conducted a cross-platform replication using the Online Coalition Game. We replicated the Strength-is-Weakness effect in a psychology laboratory, on Amazon Mechanical Turk, and on Prolific. Moreover, our results showed that the equity norm shapes the Strength-is-Weakness effect in two ways. First, strong bargainers claim a higher larger of the payoffs than weak bargainers do, making them less attractive coalition partners. Second, weak bargainers expect strong bargainers to make these larger claims, directing weak bargainers to each other from the outset. Finally, the studies suggest that the Online Coalition Game is a viable tool for conducting high-powered coalition formation research.

联盟形成的一个关键观察结果是，拥有最多资源的讨价还价者往往被排除在联盟之外：即强即弱效应。以前的研究因样本量小和缺乏（适当的）激励措施而受到影响，并且很少关注潜在的过程。为了解决这些问题，我们使用在线联盟游戏进行了跨平台复制。我们在心理学实验室、Amazon Mechanical Turk 和 Prolific 上复制了“强即弱”效应。此外，我们的结果表明，公平规范以两种方式塑造强弱效应。首先，强势讨价还价者比弱势讨价还价者要求更高的回报，这使得他们对联盟伙伴的吸引力降低。其次，弱势讨价还价者期望强势讨价还价者提出更大的要求，从而从一开始就将弱势讨价还价者引导到彼此。最后，研究表明，在线联盟游戏是进行高效联盟形成研究的可行工具。