Among studies of social species, it is common practice to rank individuals using dyadic social dominance relationships. The Elo-rating method for achieving this is powerful and increasingly popular, particularly among studies of nonhuman primates, but suffers from two deficiencies that hamper its usefulness: an initial burn-in period during which the model is unreliable and an assumption that all win–loss interactions are equivalent in their influence on rank trajectories. Here, I present R code that addresses these deficiencies by incorporating two modifications to a previously published function, testing this with data from a 9-mo observational study of social interactions among wild male chimpanzees (Pan troglodytes) in Uganda. I found that, unmodified, the R function failed to resolve a hierarchy, with the burn-in period spanning much of the study. Using the modified function, I incorporated both prior knowledge of dominance ranks and varying intensities of aggression. This effectively eliminated the burn-in period, generating rank trajectories that were consistent with the direction of pant-grunt vocalizations (an unambiguous demonstration of subordinacy) and field observations, as well as showing a clear relationship between rank and mating success. This function is likely to be particularly useful in studies that are short relative to the frequency of aggressive interactions, for longer-term data sets disrupted by periods of lower quality or missing data, and for projects investigating the relative importance of differing behaviors in driving changes in social dominance. This study highlights the need for caution when using Elo-ratings to model social dominance in nonhuman primates and other species.

中文翻译：

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社会支配地位建模：Elo-Ratings、先前的历史和侵略的强度

在对社会物种的研究中，通常的做法是使用二元社会优势关系对个体进行排名。用于实现这一目标的 Elo 评级方法功能强大且越来越受欢迎，尤其是在非人类灵长类动物的研究中，但存在两个阻碍其实用性的缺陷：模型不可靠的初始老化期以及所有获胜的假设——损失相互作用对秩轨迹的影响是等效的。在这里，我展示了通过对先前发布的函数进行两项修改来解决这些缺陷的 R 代码，并使用来自乌干达野生雄性黑猩猩（Pan troglodytes）之间社会互动的 9 个月观察性研究的数据进行测试。我发现，未经修改，R 函数无法解析层次结构，老化期跨越了大部分研究。使用修改后的函数，我结合了优势等级的先验知识和不同强度的侵略。这有效地消除了老化期，产生了与喘气咕噜声（从属的明确证明）和现场观察的方向一致的等级轨迹，并显示出等级和交配成功之间的明确关系。此功能可能在相对于积极互动频率较短的研究中特别有用，对于因较低质量或缺失数据时期而中断的长期数据集，以及调查不同行为在推动变化中的相对重要性的项目在社会支配地位。